U.S. patent application number 12/464800 was filed with the patent office on 2009-09-03 for precision control systems for tissue visualization and manipulation assemblies.
This patent application is currently assigned to VOYAGE MEDICAL, INC.. Invention is credited to Ruey-Feng PEH, Vahid SAADAT, Edmund A. TAM.
Application Number | 20090221871 12/464800 |
Document ID | / |
Family ID | 39318997 |
Filed Date | 2009-09-03 |
United States Patent
Application |
20090221871 |
Kind Code |
A1 |
PEH; Ruey-Feng ; et
al. |
September 3, 2009 |
PRECISION CONTROL SYSTEMS FOR TISSUE VISUALIZATION AND MANIPULATION
ASSEMBLIES
Abstract
Precision control systems for tissue visualization and
manipulation assemblies are described herein where such devices may
utilize a variety of apparatus and methods for facilitating
advancement, articulation, control, navigation, etc. of systems
which may be used to visual and/or treat tissue regions.
Additionally, methods and devices for enhancing navigation of the
device through a patient body are also described.
Inventors: |
PEH; Ruey-Feng; (Mountain
View, CA) ; SAADAT; Vahid; (Atherton, CA) ;
TAM; Edmund A.; (Mountain View, CA) |
Correspondence
Address: |
LEVINE BAGADE HAN LLP
2400 GENG ROAD, SUITE 120
PALO ALTO
CA
94303
US
|
Assignee: |
VOYAGE MEDICAL, INC.
Campbell
CA
|
Family ID: |
39318997 |
Appl. No.: |
12/464800 |
Filed: |
May 12, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11848429 |
Aug 31, 2007 |
|
|
|
12464800 |
|
|
|
|
60824421 |
Sep 1, 2006 |
|
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|
60916640 |
May 8, 2007 |
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Current U.S.
Class: |
600/118 |
Current CPC
Class: |
A61B 2034/2068 20160201;
A61B 2017/00084 20130101; A61B 2017/00106 20130101; A61B 1/018
20130101; A61B 1/00082 20130101; A61B 1/0008 20130101; A61B 34/20
20160201; A61B 90/36 20160201; A61B 18/24 20130101; A61B 2018/00214
20130101; A61B 18/1492 20130101; A61B 5/02007 20130101; A61B 1/015
20130101; A61B 1/04 20130101; A61B 2017/00057 20130101; A61B
2018/00375 20130101; A61B 2017/3425 20130101; A61B 1/00089
20130101; A61B 1/00085 20130101; A61B 2017/003 20130101; A61B
2018/00898 20130101; A61B 2034/2051 20160201; A61B 2034/301
20160201; A61B 2017/00053 20130101; A61B 1/005 20130101 |
Class at
Publication: |
600/118 |
International
Class: |
A61B 1/04 20060101
A61B001/04 |
Claims
1. A computer-assisted heart treatment system for treating a tissue
of a heart, wherein blood is disposed within a chamber of the
heart, comprising: an articulatable catheter defining at least one
lumen therethrough; a computer-controlled guidance assembly coupled
to the catheter; a processor coupled to the computer-controlled
guidance assembly so that the articulation of the catheter effects
repositioning of a distal portion of the catheter; an imaging
assembly positionable through the at least one lumen and configured
to obtain, while blood is disposed in the chamber, an image of a
tissue surface within the chamber, wherein repositioning of the
distal portion effects a corresponding repositioning of the imaging
assembly; and a display coupleable to the imaging assembly so as to
display the tissue surface image.
2. The system of claim 1 further comprising a tracking system
transmitting position feedback signals to the processor, wherein
the processor transmits drive signals for the computer-controlled
guidance assembly using the position feedback signals.
3. The system of claim 2 wherein the imaging assembly comprises an
imaging element and a barrier extending from a deployment catheter
positioned through the at least one lumen.
4. The system of claim 3 wherein the deployment catheter defines at
least one fluid lumen therethrough which is in communication with
an open area defined in part by the barrier such that the open area
is in communication with an environment external to the
barrier.
5. The system of claim 1 wherein the distal portion of the catheter
is movable within a first plane in response to signals from the
computer-controlled guidance assembly, and wherein the distal
portion is further movable within a second plane transverse to the
first plane in response to signals from the computer-controlled
guidance assembly.
6. The system of claim 1 wherein the computer-controlled guidance
assembly comprises one or more drive assemblies coupled to the
distal end of the catheter via a respective pullwire.
7. The system of claim 1 further comprising an instrument guidance
assembly configured to retract an outer sheath relative to the
articulatable catheter.
8. A computer assisted method of treating a tissue surface region
within a chamber of a heart, comprising: positioning a distal
portion of a catheter within the chamber, the catheter coupled to a
computer-controlled guidance assembly; articulating the catheter
with the computer-controlled guidance assembly so that movement of
the catheter within the chamber is registered; positioning a
deployment catheter having a barrier projecting from its distal end
within a lumen defined through the catheter within the chamber;
locally displacing blood with a transparent fluid from an open area
defined by the barrier which is disposed within a portion of the
chamber, the open area disposed adjacent the tissue region; and
visualizing, on a display, the tissue region within the open area
as imaged through the transparent fluid.
9. The method of claim 8 wherein positioning a distal portion
comprises advancing the distal portion of the catheter into a left
atrial chamber of a heart.
10. The method of claim 8 wherein positioning a distal portion
comprises rotating one or more drive assemblies coupled to the
distal portion of the catheter via a respective pullwire.
11. The method of claim 10 wherein rotating one or more drive
assemblies in a first rotational direction urges the catheter to
deflect in a first direction and rotating one or more drive
assemblies in a second rotational direction opposite to the first
rotational direction urges the catheter to deflect in a second
direction opposite to the first direction.
12. The method of claim 8 wherein positioning a deployment catheter
comprises deploying the barrier from a low-profile delivery
configuration within the lumen into an expanded deployed
configuration external of the distal portion of the catheter.
13. The method of claim 8 wherein positioning a deployment catheter
further comprises placing the open area of the barrier against or
adjacent to the tissue region.
14. The method of claim 8 wherein locally displacing blood
comprises infusing the transparent fluid into the open area through
a fluid delivery lumen defined through the catheter within the
chamber.
15. The method of claim 8 further comprising repositioning the
barrier relative to the tissue region by repositioning the distal
portion of the catheter within the chamber.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application 11/848,429 filed Aug. 31, 2007 which claims the benefit
of priority to U.S. Prov. Pat. App. 60/824,421 filed Sep. 1, 2006
and to U.S. Prov. Pat. App. 60/916,640 filed May 8, 2007, each of
which is incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to medical devices
used for accessing, visualizing, and/or treating regions of tissue
within a body. More particularly, the present invention relates to
systems for controlling and navigating devices used to directly
visualize and/or manipulate tissue regions within a body lumen
which are generally difficult to access and/or image.
BACKGROUND OF THE INVENTION
[0003] Conventional devices for visualizing interior regions of a
body lumen are known. For example, ultrasound devices have been
used to produce images from within a body in vivo. Ultrasound has
been used both with and without contrast agents, which typically
enhance ultrasound-derived images.
[0004] Other conventional methods have utilized catheters or probes
having position sensors deployed within the body lumen, such as the
interior of a cardiac chamber. These types of positional sensors
are typically used to determine the movement of a cardiac tissue
surface or the electrical activity within the cardiac tissue. When
a sufficient number of points have been sampled by the sensors, a
"map" of the cardiac tissue may be generated.
[0005] Another conventional device utilizes an inflatable balloon
which is typically introduced intravascularly in a deflated state
and then inflated against the tissue region to be examined. Imaging
is typically accomplished by an optical fiber or other apparatus
such as electronic chips for viewing the tissue through the
membrane(s) of the inflated balloon. Moreover, the balloon must
generally be inflated for imaging. Other conventional balloons
utilize a cavity or depression formed at a distal end of the
inflated balloon. This cavity or depression is pressed against the
tissue to be examined and is flushed with a clear fluid to provide
a clear pathway through the blood.
[0006] However, such imaging balloons have many inherent
disadvantages. For instance, such balloons generally require that
the balloon be inflated to a relatively large size which may
undesirably displace surrounding tissue and interfere with fine
positioning of the imaging system against the tissue. Moreover, the
working area created by such inflatable balloons are generally
cramped and limited in size. Furthermore, inflated balloons may be
susceptible to pressure changes in the surrounding fluid. For
example, if the environment surrounding the inflated balloon
undergoes pressure changes, e.g., during systolic and diastolic
pressure cycles in a beating heart, the constant pressure change
may affect the inflated balloon volume and its positioning to
produce unsteady or undesirable conditions for optimal tissue
imaging.
[0007] Accordingly, these types of imaging modalities are generally
unable to provide desirable images useful for sufficient diagnosis
and therapy of the endoluminal structure, due in part to factors
such as dynamic forces generated by the natural movement of the
heart. Moreover, anatomic structures within the body can occlude or
obstruct the image acquisition process. Also, the presence and
movement of opaque bodily fluids such as blood generally make in
vivo imaging of tissue regions within the heart difficult.
[0008] Other external imaging modalities are also conventionally
utilized. For example, computed tomography (CT) and magnetic
resonance imaging (MRI) are typical modalities which are widely
used to obtain images of body lumens such as the interior chambers
of the heart. However, such imaging modalities fail to provide
real-time imaging for intra-operative therapeutic procedures.
Fluoroscopic imaging, for instance, is widely used to identify
anatomic landmarks within the heart and other regions of the body.
However, fluoroscopy fails to provide an accurate image of the
tissue quality or surface and also fails to provide for
instrumentation for performing tissue manipulation or other
therapeutic procedures upon the visualized tissue regions. In
addition, fluoroscopy provides a shadow of the intervening tissue
onto a plate or sensor when it may be desirable to view the
intraluminal surface of the tissue to diagnose pathologies or to
perform some form of therapy on it.
[0009] Thus, a tissue imaging system which is able to provide
real-time in vivo images of tissue regions within body lumens such
as the heart through opaque media such as blood and which also
provide instruments for therapeutic procedures upon the visualized
tissue are desirable.
BRIEF SUMMARY OF THE INVENTION
[0010] A tissue imaging and manipulation apparatus that may be
utilized for procedures within a body lumen, such as the heart, in
which visualization of the surrounding tissue is made difficult, if
not impossible, by medium contained within the lumen such as blood,
is described below. Generally, such a tissue imaging and
manipulation apparatus comprises an optional delivery catheter or
sheath through which a deployment catheter and imaging hood may be
advanced for placement against or adjacent to the tissue to be
imaged.
[0011] The deployment catheter may define a fluid delivery lumen
therethrough as well as an imaging lumen within which an optical
imaging fiber or assembly may be disposed for imaging tissue. When
deployed, the imaging hood may be expanded into any number of
shapes, e.g., cylindrical, conical as shown, semi-spherical, etc.,
provided that an open area or field is defined by the imaging hood.
The open area is the area within which the tissue region of
interest may be imaged. The imaging hood may also define an
atraumatic contact lip or edge for placement or abutment against
the tissue region of interest. Moreover, the distal end of the
deployment catheter or separate manipulatable catheters may be
articulated through various controlling mechanisms such as
push-pull wires manually or via computer control
[0012] The deployment catheter may also be stabilized relative to
the tissue surface through various methods. For instance,
inflatable stabilizing balloons positioned along a length of the
catheter may be utilized, or tissue engagement anchors may be
passed through or along the deployment catheter for temporary
engagement of the underlying tissue.
[0013] In operation, after the imaging hood has been deployed,
fluid may be pumped at a positive pressure through the fluid
delivery lumen until the fluid fills the open area completely and
displaces any blood from within the open area. The fluid may
comprise any biocompatible fluid, e.g., saline, water, plasma,
Fluorinert.TM., etc., which is sufficiently transparent to allow
for relatively undistorted visualization through the fluid. The
fluid may be pumped continuously or intermittently to allow for
image capture by an optional processor which may be in
communication with the assembly.
[0014] In an exemplary variation for imaging tissue surfaces within
a heart chamber containing blood, the tissue imaging and treatment
system may generally comprise a catheter body having a lumen
defined therethrough, a visualization element disposed adjacent the
catheter body, the visualization element having a field of view, a
transparent fluid source in fluid communication with the lumen, and
a barrier or membrane extendable from the catheter body to
localize, between the visualization clement and the field of view,
displacement of blood by transparent fluid that flows from the
lumen, and a piercing instrument translatable through the displaced
blood for piercing into the tissue surface within the field of
view.
[0015] The imaging hood may be formed into any number of
configurations and the imaging assembly may also be utilized with
any number of therapeutic tools which may be deployed through the
deployment catheter.
[0016] Moreover, the imaging hood may be utilized with various
catheter control assemblies to provide for precise catheter motion.
For instance, robotically-controlled catheter systems may be
utilized with the imaging hood and various instruments delivered
through the hood. Alternatively, magnetic navigational systems may
also be utilized to control and/or locate a hood within the patient
body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1A shows a side view of one variation of a tissue
imaging apparatus during deployment from a sheath or delivery
catheter.
[0018] FIG. 1B shows the deployed tissue imaging apparatus of FIG.
1A having an optionally expandable hood or sheath attached to an
imaging and/or diagnostic catheter.
[0019] FIG. 1C shows an end view of a deployed imaging
apparatus.
[0020] FIGS. 1D to 1F show the apparatus of FIGS. 1A to 1C with an
additional lumen, e.g., for passage of a guidewire
therethrough.
[0021] FIGS. 2A and 2B show one example of a deployed tissue imager
positioned against or adjacent to the tissue to be imaged and a
flow of fluid, such as saline, displacing blood from within the
expandable hood.
[0022] FIG. 3A shows an articulatable imaging assembly which may be
manipulated via push-pull wires or by computer control.
[0023] FIGS. 3B and 3C show steerable instruments, respectively,
where an articulatable delivery catheter may be steered within the
imaging hood or a distal portion of the deployment catheter itself
may be steered.
[0024] FIGS. 4A to 4C show side and cross-sectional end views,
respectively, of another variation having an off-axis imaging
capability.
[0025] FIG. 5 shows an illustrative view of an example of a tissue
imager advanced intravascularly within a heart for imaging tissue
regions within an atrial chamber.
[0026] FIGS. 6A to 6C illustrate deployment catheters having one or
more optional inflatable balloons or anchors for stabilizing the
device during a procedure.
[0027] FIGS. 7A and 7B illustrate a variation of an anchoring
mechanism such as a helical tissue piercing device for temporarily
stabilizing the imaging hood relative to a tissue surface.
[0028] FIG. 7C shows another variation for anchoring the imaging
hood having one or more tubular support members integrated with the
imaging hood; each support members may define a lumen therethrough
for advancing a helical tissue anchor within.
[0029] FIG. 8A shows an illustrative example of one variation of
how a tissue imager may be utilized with an imaging device.
[0030] FIG. 8B shows a further illustration of a hand-held
variation of the fluid delivery and tissue manipulation system.
[0031] FIGS. 9A to 9C illustrate an example of capturing several
images of the tissue at multiple regions.
[0032] FIGS. 10A and 10B show charts illustrating how fluid
pressure within the imaging hood may be coordinated with the
surrounding blood pressure; the fluid pressure in the imaging hood
may be coordinated with the blood pressure or it may be regulated
based upon pressure feedback from the blood.
[0033] FIG. 11A shows a side view of another variation of a tissue
imager having an imaging balloon within an expandable hood.
[0034] FIG. 11B shows another variation of a tissue imager
utilizing a translucent or transparent imaging balloon.
[0035] FIG. 12A shows another variation in which a flexible
expandable or distensible membrane may be incorporated within the
imaging hood to alter the volume of fluid dispensed.
[0036] FIGS. 12B and 12C show another variation in which the
imaging hood may be partially or selectively deployed from the
catheter to alter the area of the tissue being visualized as well
as the volume of the dispensed fluid.
[0037] FIGS. 13A and 13B show exemplary side and cross-sectional
views, respectively, of another variation in which the injected
fluid may be drawn back into the device for minimizing fluid input
into a body being treated.
[0038] FIGS. 14A to 14D show various configurations and methods for
configuring an imaging hood into a low-profile for delivery and/or
deployment.
[0039] FIGS. 15A and 15B show an imaging hood having an helically
expanding frame or support.
[0040] FIGS. 16A and 16B show another imaging hood having one or
more hood support members, which are pivotably attached at their
proximal ends to deployment catheter, integrated with a hood
membrane.
[0041] FIGS. 17A and 17B show yet another variation of the imaging
hood having at least two or more longitudinally positioned support
members supporting the imaging hood membrane where the support
members are movable relative to one another via a torquing or
pulling or pushing force.
[0042] FIGS. 18A and 18B show another variation where a distal
portion of the deployment catheter may have several pivoting
members which form a tubular shape in its low profile
configuration.
[0043] FIGS. 19A and 19B show another variation where the distal
portion of deployment catheter may be fabricated from a flexible
metallic or polymeric material to form a radially expanding
hood.
[0044] FIGS. 20A and 20B show another variation where the imaging
hood may be formed from a plurality of overlapping hood members
which overlie one another in an overlapping pattern.
[0045] FIGS. 21A and 21B show another example of an expandable hood
which is highly conformable against tissue anatomy with varying
geography.
[0046] FIG. 22A shows yet another example of an expandable hood
having a number of optional electrodes placed about the contact
edge or lip of the hood for sensing tissue contact or detecting
arrhythmias.
[0047] FIG. 22B shows another variation for conforming the imaging
hood against the underlying tissue where an inflatable contact edge
may be disposed around the circumference of the imaging hood.
[0048] FIG. 23 shows a variation of the system which may be
instrumented with a transducer for detecting the presence of blood
seeping back into the imaging hood.
[0049] FIGS. 24A and 24B show variations of the imaging hood
instrumented with sensors for detecting various physical
parameters; the sensors may be instrumented around the outer
surface of the imaging hood and also within the imaging hood.
[0050] FIGS. 25A and 25B show a variation where the imaging hood
may have one or more LEDs over the hood itself for providing
illumination of the tissue to be visualized.
[0051] FIGS. 26A and 26B show another variation in which a separate
illumination tool having one or more LEDs mounted thereon may be
utilized within the imaging hood.
[0052] FIG. 27 shows one example of how a therapeutic tool may be
advanced through the tissue imager for treating a tissue region of
interest.
[0053] FIG. 28 shows another example of a helical therapeutic tool
for treating the tissue region of interest.
[0054] FIG. 29 shows a variation of how a therapeutic tool may be
utilized with an expandable imaging balloon.
[0055] FIGS. 30A and 30B show alternative configurations for
therapeutic instruments which may be utilized; one variation is
shown having an angled instrument arm and another variation is
shown with an off-axis instrument ann.
[0056] FIGS. 31A to 31C show side and end views, respectively, of
an imaging system which may be utilized with an ablation probe.
[0057] FIGS. 32A and 32B show side and end views, respectively, of
another variation of the imaging hood with an ablation probe, where
the imaging hood may be enclosed for regulating a temperature of
the underlying tissue.
[0058] FIGS. 33A and 33B show an example in which the imaging fluid
itself may be altered in temperature to facilitate various
procedures upon the underlying tissue.
[0059] FIGS. 34A and 34B show an example of a laser ring generator
which may be utilized with the imaging system and an example for
applying the laser ring generator within the left atrium of a heart
for treating atrial fibrillation.
[0060] FIGS. 35A to 35C show an example of an extendible cannula
generally comprising an elongate tubular member which may be
positioned within the deployment catheter during delivery and then
projected distally through the imaging hood and optionally
beyond.
[0061] FIGS. 36A and 36B show side and end views, respectively, of
an imaging hood having one or more tubular support members
integrated with the hood for passing instruments or tools
therethrough for treatment upon the underlying tissue.
[0062] FIGS. 37A and 37B illustrate how an imaging device may be
guided within a heart chamber to a region of interest utilizing a
lighted probe positioned temporarily within, e.g., a lumen of the
coronary sinus.
[0063] FIGS. 38A and 38B show an imaging hood having a removable
disk-shaped member for implantation upon the tissue surface.
[0064] FIGS. 39A to 39C show one method for implanting the
removable disk of FIGS. 38A and 38B.
[0065] FIGS. 40A and 40B illustrate an imaging hood having a
deployable anchor assembly attached to the tissue contact edge and
an assembly view of the anchors and the suture or wire connected to
the anchors, respectively
[0066] FIGS. 41A to 41D show one method for deploying the anchor
assembly of FIGS. 40A and 40B for closing an opening or wound.
[0067] FIG. 42 shows another variation in which the imaging system
may be fluidly coupled to a dialysis unit for filtering a patient's
blood.
[0068] FIGS. 43A and 43B show a variation of the deployment
catheter having a first deployable hood and a second deployable
hood positioned distal to the first hood; the deployment catheter
may also have a side-viewing imaging element positioned between the
first and second hoods for imaging tissue between the expanded
hoods.
[0069] FIGS. 44A and 44B show side and end views, respectively, of
a deployment catheter having a side-imaging balloon in an
un-inflated low-profile configuration.
[0070] FIGS. 45A to 45C show side, top, and end views,
respectively, of the inflated balloon of FIGS. 44A and 44B defining
a visualization field in the inflated balloon.
[0071] FIGS. 46A and 46B show side and cross-sectional end views,
respectively, for one method of use in visualizing a lesion upon a
vessel wall within the visualization field of the inflated balloon
from FIGS. 45A to 45C.
[0072] FIGS. 47A and 47B show assembly views of examples of a
robotically-controlled guide instrument for precisely controlling a
position of a hood.
[0073] FIG. 47C illustrates an example of how a robotic guide
instrument may be utilized with a visualization system.
[0074] FIGS. 48A and 48B show perspective views of a variation of a
robotic control assembly showing base having four proximal drive
assemblies and the imaging hood positioned at a distal end of the
catheter.
[0075] FIG. 48C illustrates a perspective view of another variation
of a robotic control assembly having an inflatable imaging balloon
assembly.
[0076] FIG. 49 shows a partially disassembled perspective view of
the precision control driver.
[0077] FIG. 50 shows a perspective assembly view of the guide
instrument mounted upon an instrument driver.
[0078] FIG. 51 shows the partially disassembled perspective view of
the catheter instrument driver.
[0079] FIGS. 52A and 52B show perspective views of another
variation of the tissue visualization catheter with precision
control steering.
[0080] FIG. 53 illustrates an example of a simplified assembly view
of the mechanisms within the control drive unit for controlling the
articulation of hood.
[0081] FIGS. 54A and 54B show an assembled view and exploded
assembly view, respectively, of a tissue visualization hood having
a pivotably articulating steering assembly.
[0082] FIGS. 55A to 55C show an assembled view, detailed spine, and
exploded assembly view, respectively, of a tissue visualization
hood utilizing steerable spine segments.
[0083] FIGS. 56A to 56C show another variation in an assembled
view, detailed spine, and exploded assembly view, respectively, of
a tissue visualization hood also utilizing steerable spine
segments.
[0084] FIG. 57A shows a perspective view of a hood having a
ferromagnetic ring attached circumferentially around the lip of the
hood.
[0085] FIG. 57B shows a perspective view of an example of a
magnetic navigation system which may be used to steer the imaging
hood through the patient body.
[0086] FIG. 58 shows a perspective view of another variation of the
tissue visualization catheter which is configured to detect the
position and/or orientation of the hood via ultrasound transducers
and having a magnetic ring circumferentially positioned about the
lip of the hood.
[0087] FIG. 59 shows a perspective view of another variation of the
tissue visualization catheter which is configured to detect the
position and/or orientation of the hood via ultrasound transducers
and having electromagnetic coils wound about one or more
struts.
[0088] FIG. 60 shows a perspective view of another variation of the
tissue visualization catheter having a ferromagnetic disc
positioned within the hood.
[0089] FIG. 61 shows a perspective view of a position sensor
assembly which may be utilized to detect an orientation and/or
location of the hood within the body as well as to draw the hood
against an internal tissue region.
[0090] FIG. 62 illustrates an example of triangulation of the
transducers to determine the orientation and position of the hood
within a patient body.
[0091] FIGS. 63A to 63C illustrate an example for orienting and
drawing a hood within a left atrial chamber against the tissue
surface to "walk" the hood along the tissue wall to visually survey
the underlying surface.
[0092] FIG. 64 illustrates another example where a catheter having
several transducers may be positioned within the coronary sinus to
communicate with the hood.
DETAILED DESCRIPTION OF THE INVENTION
[0093] A tissue-imaging and manipulation apparatus described below
is able to provide real-time images in vivo of tissue regions
within a body lumen such as a heart, which is filled with blood
flowing dynamically therethrough and is also able to provide
intravascular tools and instruments for performing various
procedures upon the imaged tissue regions. Such an apparatus may be
utilized for many procedures, e.g., facilitating transseptal access
to the left atrium, cannulating the coronary sinus, diagnosis of
valve regurgitation/stenosis, valvuloplasty, atrial appendage
closure, arrhythmogenic focus ablation, among other procedures.
[0094] One variation of a tissue access and imaging apparatus is
shown in the detail perspective views of FIGS. 1A to 1C. As shown
in FIG. 1A, tissue imaging and manipulation assembly 10 may be
delivered intravascularly through the patient's body in a
low-profile configuration via a delivery catheter or sheath 14. In
the case of treating tissue, such as the mitral valve located at
the outflow tract of the left atrium of the heart, it is generally
desirable to enter or access the left atrium while minimizing
trauma to the patient. To non-operatively effect such access, one
conventional approach involves puncturing the intra-atrial septum
from the right atrial chamber to the left atrial chamber in a
procedure commonly called a transseptal procedure or septostomy.
For procedures such as percutaneous valve repair and replacement,
transseptal access to the left atrial chamber of the heart may
allow for larger devices to be introduced into the venous system
than can generally be introduced percutaneously into the arterial
system.
[0095] When the imaging and manipulation assembly 10 is ready to be
utilized for imaging tissue, imaging hood 12 may be advanced
relative to catheter 14 and deployed from a distal opening of
catheter 14, as shown by the arrow. Upon deployment, imaging hood
12 may be unconstrained to expand or open into a deployed imaging
configuration, as shown in FIG. 1B. Imaging hood 12 may be
fabricated from a variety of pliable or conformable biocompatible
material including but not limited to, e.g., polymeric, plastic, or
woven materials. One example of a woven material is Kevlar) (E. I.
du Pont de Nemours, Wilmington, Del.), which is an aramid and which
can be made into thin, e.g., less than 0.001 in., materials which
maintain enough integrity for such applications described herein.
Moreover, the imaging hood 12 may be fabricated from a translucent
or opaque material and in a variety of different colors to optimize
or attenuate any reflected lighting from surrounding fluids or
structures, i.e., anatomical or mechanical structures or
instruments. In either case, imaging hood 12 may be fabricated into
a uniform structure or a scaffold-supported structure, in which
case a scaffold made of a shape memory alloy, such as Nitinol, or a
spring steel, or plastic, etc., may be fabricated and covered with
the polymeric, plastic, or woven material. Hence, imaging hood 12
may comprise any of a wide variety of barriers or membrane
structures, as may generally be used to localize displacement of
blood or the like from a selected volume of a body lumen or heart
chamber. In exemplary embodiments, a volume within an inner surface
13 of imaging hood 12 will be significantly less than a volume of
the hood 12 between inner surface 13 and outer surface 11.
[0096] Imaging hood 12 may be attached at interface 24 to a
deployment catheter 16 which may be translated independently of
deployment catheter or sheath 14. Attachment of interface 24 may be
accomplished through any number of conventional methods. Deployment
catheter 16 may define a fluid delivery lumen 18 as well as an
imaging lumen 20 within which an optical imaging fiber or assembly
may be disposed for imaging tissue. When deployed, imaging hood 12
may expand into any number of shapes, e.g., cylindrical, conical as
shown, semi-spherical, etc., provided that an open area or field 26
is defined by imaging hood 12. The open area 26 is the area within
which the tissue region of interest may be imaged. Imaging hood 12
may also define an atraumatic contact lip or edge 22 for placement
or abutment against the tissue region of interest. Moreover, the
diameter of imaging hood 12 at its maximum fully deployed diameter,
e.g., at contact lip or edge 22, is typically greater relative to a
diameter of the deployment catheter 16 (although a diameter of
contact lip or edge 22 may be made to have a smaller or equal
diameter of deployment catheter 16). For instance, the contact edge
diameter may range anywhere from 1 to 5 times (or even greater, as
practicable) a diameter of deployment catheter 16. FIG. 1C shows an
end view of the imaging hood 12 in its deployed configuration. Also
shown are the contact lip or edge 22 and fluid delivery lumen 18
and imaging lumen 20.
[0097] The imaging and manipulation assembly 10 may additionally
define a guidewire lumen therethrough, e.g., a concentric or
eccentric lumen, as shown in the side and end views, respectively,
of FIGS. 1D to 1F. The deployment catheter 16 may define guidewire
lumen 19 for facilitating the passage of the system over or along a
guidewire 17, which may be advanced intravascularly within a body
lumen. The deployment catheter 16 may then be advanced over the
guidewire 17, as generally known in the art.
[0098] In operation, after imaging hood 12 has been deployed, as in
FIG. 1B, and desirably positioned against the tissue region to be
imaged along contact edge 22, the displacing fluid may be pumped at
positive pressure through fluid delivery lumen 18 until the fluid
fills open area 26 completely and displaces any fluid 28 from
within open area 26. The displacing fluid flow may be laminarized
to improve its clearing effect and to help prevent blood from
re-entering the imaging hood 12. Alternatively, fluid flow may be
started before the deployment takes place. The displacing fluid,
also described herein as imaging fluid, may comprise any
biocompatible fluid, e.g., saline, water, plasma, etc., which is
sufficiently transparent to allow for relatively undistorted
visualization through the fluid. Alternatively or additionally, any
number of therapeutic drugs may be suspended within the fluid or
may comprise the fluid itself which is pumped into open area 26 and
which is subsequently passed into and through the heart and the
patient body.
[0099] As seen in the example of FIGS. 2A and 2B, deployment
catheter 16 may be manipulated to position deployed imaging hood 12
against or near the underlying tissue region of interest to be
imaged, in this example a portion of annulus A of mitral valve MV
within the left atrial chamber. As the surrounding blood 30 flows
around imaging hood 12 and within open area 26 defined within
imaging hood 12, as seen in FIG. 2A, the underlying annulus A is
obstructed by the opaque blood 30 and is difficult to view through
the imaging lumen 20. The translucent fluid 28, such as saline, may
then be pumped through fluid delivery lumen 18, intermittently or
continuously, until the blood 30 is at least partially, and
preferably completely, displaced from within open area 26 by fluid
28, as shown in FIG. 2B.
[0100] Although contact edge 22 need not directly contact the
underlying tissue, it is at least preferably brought into close
proximity to the tissue such that the flow of clear fluid 28 from
open area 26 may be maintained to inhibit significant backflow of
blood 30 back into open area 26. Contact edge 22 may also be made
of a soft elastomeric material such as certain soft grades of
silicone or polyurethane, as typically known, to help contact edge
22 conform to an uneven or rough underlying anatomical tissue
surface. Once the blood 30 has been displaced from imaging hood 12,
an image may then be viewed of the underlying tissue through the
clear fluid 30. This image may then be recorded or available for
real-time viewing for performing a therapeutic procedure. The
positive flow of fluid 28 may be maintained continuously to provide
for clear viewing of the underlying tissue. Alternatively, the
fluid 28 may be pumped temporarily or sporadically only until a
clear view of the tissue is available to be imaged and recorded, at
which point the fluid flow 28 may cease and blood 30 may be allowed
to seep or flow back into imaging hood 12. This process may be
repeated a number of times at the same tissue region or at multiple
tissue regions.
[0101] In desirably positioning the assembly at various regions
within the patient body, a number of articulation and manipulation
controls may be utilized. For example, as shown in the
articulatable imaging assembly 40 in FIG. 3A, one or more push-pull
wires 42 may be routed through deployment catheter 16 for steering
the distal end portion of the device in various directions 46 to
desirably position the imaging hood 12 adjacent to a region of
tissue to be visualized. Depending upon the positioning and the
number of push-pull wires 42 utilized, deployment catheter 16 and
imaging hood 12 may be articulated into any number of
configurations 44. The push-pull wire or wires 42 may be
articulated via their proximal ends from outside the patient body
manually utilizing one or more controls. Alternatively, deployment
catheter 16 may be articulated by computer control, as further
described below.
[0102] Additionally or alternatively, an articulatable delivery
catheter 48, which may be articulated via one or more push-pull
wires and having an imaging lumen and one or more working lumens,
may be delivered through the deployment catheter 16 and into
imaging hood 12. With a distal portion of articulatable delivery
catheter 48 within imaging hood 12, the clear displacing fluid may
be pumped through delivery catheter 48 or deployment catheter 16 to
clear the field within imaging hood 12. As shown in FIG. 3B, the
articulatable delivery catheter 48 may be articulated within the
imaging hood to obtain a better image of tissue adjacent to the
imaging hood 12. Moreover, articulatable delivery catheter 48 may
be articulated to direct an instrument or tool passed through the
catheter 48, as described in detail below, to specific areas of
tissue imaged through imaging hood 12 without having to reposition
deployment catheter 16 and re-clear the imaging field within hood
12.
[0103] Alternatively, rather than passing an articulatable delivery
catheter 48 through the deployment catheter 16, a distal portion of
the deployment catheter 16 itself may comprise a distal end 49
which is articulatable within imaging hood 12, as shown in FIG. 3C.
Directed imaging, instrument delivery, etc., may be accomplished
directly through one or more lumens within deployment catheter 16
to specific regions of the underlying tissue imaged within imaging
hood 12.
[0104] Visualization within the imaging hood 12 may be accomplished
through an imaging lumen 20 defined through deployment catheter 16,
as described above. In such a configuration, visualization is
available in a straight-line manner, i.e., images are generated
from the field distally along a longitudinal axis defined by the
deployment catheter 16. Alternatively or additionally, an
articulatable imaging assembly having a pivotable support member 50
may be connected to, mounted to, or otherwise passed through
deployment catheter 16 to provide for visualization off-axis
relative to the longitudinal axis defined by deployment catheter
16, as shown in FIG. 4A. Support member 50 may have an imaging
element 52. e.g., a CCD or CMOS imager or optical fiber, attached
at its distal end with its proximal end connected to deployment
catheter 16 via a pivoting connection 54.
[0105] If one or more optical fibers are utilized for imaging, the
optical fibers 58 may be passed through deployment catheter 16, as
shown in the cross-section of FIG. 4B, and routed through the
support member 50. The use of optical fibers 58 may provide for
increased diameter sizes of the one or several lumens 56 through
deployment catheter 16 for the passage of diagnostic and/or
therapeutic tools therethrough. Alternatively, electronic chips,
such as a charge coupled device (CCD) or a CMOS imager, which are
typically known, may be utilized in place of the optical fibers 58,
in which case the electronic imager may be positioned in the distal
portion of the deployment catheter 16 with electric wires being
routed proximally through the deployment catheter 16.
Alternatively, the electronic imagers may be wirelessly coupled to
a receiver for the wireless transmission of images. Additional
optical fibers or light emitting diodes (LEDs) can be used to
provide lighting for the image or operative theater, as described
below in further detail. Support member 50 may be pivoted via
connection 54 such that the member 50 can be positioned in a
low-profile configuration within channel or groove 60 defined in a
distal portion of catheter 16, as shown in the cross-section of
FIG. 4C. During intravascular delivery of deployment catheter 16
through the patient body, support member 50 can be positioned
within channel or groove 60 with imaging hood 12 also in its
low-profile configuration. During visualization, imaging hood 12
may be expanded into its deployed configuration and support member
50 may be deployed into its off-axis configuration for imaging the
tissue adjacent to hood 12, as in FIG. 4A. Other configurations for
support member 50 for off-axis visualization may be utilized, as
desired.
[0106] FIG. 5 shows an illustrative cross-sectional view of a heart
H having tissue regions of interest being viewed via an imaging
assembly 10. In this example, delivery catheter assembly 76 may be
introduced percutaneously into the patient's vasculature and
advanced through the superior vena cava SVC and into the right
atrium RA. The delivery catheter or sheath 72 may be articulated
through the atrial septum AS and into the left atrium LA for
viewing or treating the tissue, e.g., the annulus A, surrounding
the mitral valve MV. As shown, deployment catheter 16 and imaging
hood 12 may be advanced out of delivery catheter 72 and brought
into contact or in proximity to the tissue region of interest. In
other examples, delivery catheter assembly 70 may be advanced
through the inferior vena cava IVC, if so desired. Moreover, other
regions of the heart H, e.g., the right ventricle RV or left
ventricle LV, may also be accessed and imaged or treated by imaging
assembly 10.
[0107] In accessing regions of the heart H or other parts of the
body, the delivery catheter or sheath 14 may comprise a
conventional intra-vascular catheter or an endoluminal delivery
device. Alternatively, robotically-controlled delivery catheters
may also be optionally utilized with the imaging assembly described
herein, in which case a computer-controller 74 may be used to
control the articulation and positioning of the delivery catheter
14. An example of a robotically-controlled delivery catheter which
may be utilized is described in further detail in U.S. Pat. Pub.
2002/0087169 A1 to Brock et al. entitled "Flexible Instrument",
which is incorporated herein by reference in its entirety. Other
robotically-controlled delivery catheters manufactured by Hansen
Medical, Inc. (Mountain View, Calif.) may also be utilized with the
delivery catheter 14, as described in further detail below.
[0108] To facilitate stabilization of the deployment catheter 16
during a procedure. one or more inflatable balloons or anchors 76
may be positioned along the length of catheter 16, as shown in FIG.
6A. For example, when utilizing a transseptal approach across the
atrial septum AS into the left atrium LA, the inflatable balloons
76 may be inflated from a low-profile into their expanded
configuration to temporarily anchor or stabilize the catheter 16
position relative to the heart H. FIG. 6B shows a first balloon 78
inflated while FIG. 6C also shows a second balloon 80 inflated
proximal to the first balloon 78. In such a configuration, the
septal wall AS may be wedged or sandwiched between the balloons 78,
80 to temporarily stabilize the catheter 16 and imaging hood 12. A
single balloon 78 or both balloons 78, 80 may be used. Other
alternatives may utilize expandable mesh members, malecots, or any
other temporary expandable structure. After a procedure has been
accomplished, the balloon assembly 76 may be deflated or
re-configured into a low-profile for removal of the deployment
catheter 16.
[0109] To further stabilize a position of the imaging hood 12
relative to a tissue surface to be imaged, various anchoring
mechanisms may be optionally employed for temporarily holding the
imaging hood 12 against the tissue. Such anchoring mechanisms may
be particularly useful for imaging tissue which is subject to
movement, e.g., when imaging tissue within the chambers of a
beating heart. A tool delivery catheter 82 having at least one
instrument lumen and an optional visualization lumen may be
delivered through deployment catheter 16 and into an expanded
imaging hood 12. As the imaging hood 12 is brought into contact
against a tissue surface T to be examined, anchoring mechanisms
such as a helical tissue piercing device 84 may be passed through
the tool delivery catheter 82, as shown in FIG. 7A, and into
imaging hood 12.
[0110] The helical tissue engaging device 84 may be torqued from
its proximal end outside the patient body to temporarily anchor
itself into the underlying tissue surface T. Once embedded within
the tissue T, the helical tissue engaging device 84 may be pulled
proximally relative to deployment catheter 16 while the deployment
catheter 16 and imaging hood 12 are pushed distally, as indicated
by the arrows in FIG. 7B, to gently force the contact edge or lip
22 of imaging hood against the tissue T. The positioning of the
tissue engaging device 84 may be locked temporarily relative to the
deployment catheter 16 to ensure secure positioning of the imaging
hood 12 during a diagnostic or therapeutic procedure within the
imaging hood 12. After a procedure, tissue engaging device 84 may
be disengaged from the tissue by torquing its proximal end in the
opposite direction to remove the anchor form the tissue T and the
deployment catheter 16 may be repositioned to another region of
tissue where the anchoring process may be repeated or removed from
the patient body. The tissue engaging device 84 may also be
constructed from other known tissue engaging devices such as
vacuum-assisted engagement or grasper-assisted engagement tools,
among others.
[0111] Although a helical anchor 84 is shown, this is intended to
be illustrative and other types of temporary anchors may be
utilized, e.g., hooked or barbed anchors, graspers, etc. Moreover,
the tool delivery catheter 82 may be omitted entirely and the
anchoring device may be delivered directly through a lumen defined
through the deployment catheter 16.
[0112] In another variation where the tool delivery catheter 82 may
be omitted entirely to temporarily anchor imaging hood 12, FIG. 7C
shows an imaging hood 12 having one or more tubular support members
86, e.g., four support members 86 as shown, integrated with the
imaging hood 12. The tubular support members 86 may define lumens
therethrough each having helical tissue engaging devices 88
positioned within. When an expanded imaging hood 12 is to be
temporarily anchored to the tissue, the helical tissue engaging
devices 88 may be urged distally to extend from imaging hood 12 and
each may be torqued from its proximal end to engage the underlying
tissue T. Each of the helical tissue engaging devices 88 may be
advanced through the length of deployment catheter 16 or they may
be positioned within tubular support members 86 during the delivery
and deployment of imaging hood 12. Once the procedure within
imaging hood 12 is finished, each of the tissue engaging devices 88
may be disengaged from the tissue and the imaging hood 12 may be
repositioned to another region of tissue or removed from the
patient body.
[0113] An illustrative example is shown in FIG. 8A of a tissue
imaging assembly connected to a fluid delivery system 90 and to an
optional processor 98 and image recorder and/or viewer 100. The
fluid delivery system 90 may generally comprise a pump 92 and an
optional valve 94 for controlling the flow rate of the fluid into
the system. A fluid reservoir 96, fluidly connected to pump 92, may
hold the fluid to be pumped through imaging hood 12. An optional
central processing unit or processor 98 may be in electrical
communication with fluid delivery system 90 for controlling flow
parameters such as the flow rate and/or velocity of the pumped
fluid. The processor 98 may also be in electrical communication
with an image recorder and/or viewer 100 for directly viewing the
images of tissue received from within imaging hood 12. Imager
recorder and/or viewer 100 may also be used not only to record the
image but also the location of the viewed tissue region, if so
desired.
[0114] Optionally, processor 98 may also be utilized to coordinate
the fluid flow and the image capture. For instance, processor 98
may be programmed to provide for fluid flow from reservoir 96 until
the tissue area has been displaced of blood to obtain a clear
image. Once the image has been determined to be sufficiently clear,
either visually by a practitioner or by computer, an image of the
tissue may be captured automatically by recorder 100 and pump 92
may be automatically stopped or slowed by processor 98 to cease the
fluid flow into the patient. Other variations for fluid delivery
and image capture are, of course, possible and the aforementioned
configuration is intended only to be illustrative and not
limiting.
[0115] FIG. 8B shows a further illustration of a hand-held
variation of the fluid delivery and tissue manipulation system 110.
In this variation, system 110 may have a housing or handle assembly
112 which can be held or manipulated by the physician from outside
the patient body. The fluid reservoir 114, shown in this variation
as a syringe, can be fluidly coupled to the handle assembly 112 and
actuated via a pumping mechanism 116, e.g., lead screw. Fluid
reservoir 114 may be a simple reservoir separated from the handle
assembly 112 and fluidly coupled to handle assembly 112 via one or
more tubes. The fluid flow rate and other mechanisms may be metered
by the electronic controller 118.
[0116] Deployment of imaging hood 12 may be actuated by a hood
deployment switch 120 located on the handle assembly 112 while
dispensation of the fluid from reservoir 114 may be actuated by a
fluid deployment switch 122, which can be electrically coupled to
the controller 118. Controller 118 may also be electrically coupled
to a wired or wireless antenna 124 optionally integrated with the
handle assembly 112, as shown in the figure. The wireless antenna
124 can be used to wirelessly transmit images captured from the
imaging hood 12 to a receiver, e.g., via Bluetooth.RTM. wireless
technology (Bluetooth SIG, Inc., Bellevue, Wash.), RF, etc., for
viewing on a monitor 128 or for recording for later viewing.
[0117] Articulation control of the deployment catheter 16, or a
delivery catheter or sheath 14 through which the deployment
catheter 16 may be delivered, may be accomplished by computer
control, as described above, in which case an additional controller
may be utilized with handle assembly 112. In the case of manual
articulation, handle assembly 112 may incorporate one or more
articulation controls 126 for manual manipulation of the position
of deployment catheter 16. Handle assembly 112 may also define one
or more instrument ports 130 through which a number of
intravascular tools may be passed for tissue manipulation and
treatment within imaging hood 12, as described further below.
Furthermore, in certain procedures, fluid or debris may be sucked
into imaging hood 12 for evacuation from the patient body by
optionally fluidly coupling a suction pump 132 to handle assembly
112 or directly to deployment catheter 16.
[0118] As described above, fluid may be pumped continuously into
imaging hood 12 to provide for clear viewing of the underlying
tissue. Alternatively, fluid may be pumped temporarily or
sporadically only until a clear view of the tissue is available to
be imaged and recorded, at which point the fluid flow may cease and
the blood may be allowed to seep or flow back into imaging hood 12.
FIGS. 9A to 9C illustrate an example of capturing several images of
the tissue at multiple regions. Deployment catheter 16 may be
desirably positioned and imaging hood 12 deployed and brought into
position against a region of tissue to be imaged, in this example
the tissue surrounding a mitral valve MV within the left atrium of
a patient's heart. The imaging hood 12 may be optionally anchored
to the tissue, as described above, and then cleared by pumping the
imaging fluid into the hood 12. Once sufficiently clear, the tissue
may be visualized and the image captured by control electronics
118. The first captured image 140 may be stored and/or transmitted
wirelessly 124 to a monitor 128 for viewing by the physician, as
shown in FIG. 9A.
[0119] The deployment catheter 16 may be then repositioned to an
adjacent portion of mitral valve MV, as shown in FIG. 9B, where the
process may be repeated to capture a second image 142 for viewing
and/or recording. The deployment catheter 16 may again be
repositioned to another region of tissue, as shown in FIG. 9C,
where a third image 144 may be captured for viewing and/or
recording. This procedure may be repeated as many times as
necessary for capturing a comprehensive image of the tissue
surrounding mitral valve MV, or any other tissue region. When the
deployment catheter 16 and imaging hood 12 is repositioned from
tissue region to tissue region, the pump may be stopped during
positioning and blood or surrounding fluid may be allowed to enter
within imaging hood 12 until the tissue is to be imaged, where the
imaging hood 12 may be cleared, as above.
[0120] As mentioned above, when the imaging hood 12 is cleared by
pumping the imaging fluid within for clearing the blood or other
bodily fluid, the fluid may be pumped continuously to maintain the
imaging fluid within the hood 12 at a positive pressure or it may
be pumped under computer control for slowing or stopping the fluid
flow into the hood 12 upon detection of various parameters or until
a clear image of the underlying tissue is obtained. The control
electronics 118 may also be programmed to coordinate the fluid flow
into the imaging hood 12 with various physical parameters to
maintain a clear image within imaging hood 12.
[0121] One example is shown in FIG. 10A which shows a chart 150
illustrating how fluid pressure within the imaging hood 12 may be
coordinated with the surrounding blood pressure. Chart 150 shows
the cyclical blood pressure 156 alternating between diastolic
pressure 152 and systolic pressure 154 over time T due to the
beating motion of the patient heart. The fluid pressure of the
imaging fluid, indicated by plot 160, within imaging hood 12 may be
automatically timed to correspond to the blood pressure changes 160
such that an increased pressure is maintained within imaging hood
12 which is consistently above the blood pressure 156 by a slight
increase .DELTA.P, as illustrated by the pressure difference at the
peak systolic pressure 158. This pressure difference, .DELTA.P, may
be maintained within imaging hood 12 over the pressure variance of
the surrounding blood pressure to maintain a positive imaging fluid
pressure within imaging hood 12 to maintain a clear view of the
underlying tissue. One benefit of maintaining a constant .DELTA.P
is a constant flow and maintenance of a clear field.
[0122] FIG. 10B shows a chart 162 illustrating another variation
for maintaining a clear view of the underlying tissue where one or
more sensors within the imaging hood 12, as described in further
detail below, may be configured to sense pressure changes within
the imaging hood 12 and to correspondingly increase the imaging
fluid pressure within imaging hood 12. This may result in a time
delay, .DELTA.T, as illustrated by the shifted fluid pressure 160
relative to the cycling blood pressure 156, although the time
delays .DELTA.T may be negligible in maintaining the clear image of
the underlying tissue. Predictive software algorithms can also be
used to substantially eliminate this time delay by predicting when
the next pressure wave peak will arrive and by increasing the
pressure ahead of the pressure wave's arrival by an amount of time
equal to the aforementioned time delay to essentially cancel the
time delay out.
[0123] The variations in fluid pressure within imaging hood 12 may
be accomplished in part due to the nature of imaging hood 12. An
inflatable balloon, which is conventionally utilized for imaging
tissue, may be affected by the surrounding blood pressure changes.
On the other hand, an imaging hood 12 retains a constant volume
therewithin and is structurally unaffected by the surrounding blood
pressure changes, thus allowing for pressure increases therewithin.
The material that hood 12 is made from may also contribute to the
manner in which the pressure is modulated within this hood 12. A
stiffer hood material, such as high durometer polyurethane or
Nylon, may facilitate the maintaining of an open hood when
deployed. On the other hand, a relatively lower durometer or softer
material, such as a low durometer PVC or polyurethane, may collapse
from the surrounding fluid pressure and may not adequately maintain
a deployed or expanded hood.
[0124] Turning now to the imaging hood, other variations of the
tissue imaging assembly may be utilized, as shown in FIG. 11A,
which shows another variation comprising an additional imaging
balloon 172 within an imaging hood 174. In this variation, an
expandable balloon 172 having a translucent skin may be positioned
within imaging hood 174. Balloon 172 may be made from any
distensible biocompatible material having sufficient translucent
properties which allow for visualization therethrough. Once the
imaging hood 174 has been deployed against the tissue region of
interest, balloon 172 may be filled with a fluid, such as saline,
or less preferably a gas, until balloon 172 has been expanded until
the blood has been sufficiently displaced. The balloon 172 may thus
be expanded proximal to or into contact against the tissue region
to be viewed. The balloon 172 can also be filled with contrast
media to allow it to be viewed on fluoroscopy to aid in its
positioning. The imager, e.g., fiber optic, positioned within
deployment catheter 170 may then be utilized to view the tissue
region through the balloon 172 and any additional fluid which may
be pumped into imaging hood 174 via one or more optional fluid
ports 176, which may be positioned proximally of balloon 172 along
a portion of deployment catheter 170. Alternatively, balloon 172
may define one or more holes over its surface which allow for
seepage or passage of the fluid contained therein to escape and
displace the blood from within imaging hood 174.
[0125] FIG. 11B shows another alternative in which balloon 180 may
be utilized alone. Balloon 180, attached to deployment catheter
178, may be filled with fluid, such as saline or contrast media,
and is preferably allowed to come into direct contact with the
tissue region to be imaged.
[0126] FIG. 12A shows another alternative in which deployment
catheter 16 incorporates imaging hood 12, as above, and includes an
additional flexible membrane 182 within imaging hood 12. Flexible
membrane 182 may be attached at a distal end of catheter 16 and
optionally at contact edge 22. Imaging hood 12 may be utilized, as
above, and membrane 182 may be deployed from catheter 16 in vivo or
prior to placing catheter 16 within a patient to reduce the volume
within imaging hood 12. The volume may be reduced or minimized to
reduce the amount of fluid dispensed for visualization or simply
reduced depending upon the area of tissue to be visualized.
[0127] FIGS. 12B and 12C show yet another alternative in which
imaging hood 186 may be withdrawn proximally within deployment
catheter 184 or deployed distally from catheter 186, as shown, to
vary the volume of imaging hood 186 and thus the volume of
dispensed fluid. Imaging hood 186 may be seen in FIG. 12B as being
partially deployed from, e.g., a circumferentially defined lumen
within catheter 184, such as annular lumen 188. The underlying
tissue may be visualized with imaging hood 186 only partially
deployed. Alternatively, imaging hood 186' may be fully deployed,
as shown in FIG. 12C, by urging hood 186' distally out from annular
lumen 188. In this expanded configuration, the area of tissue to be
visualized may be increased as hood 186' is expanded
circumferentially.
[0128] FIGS. 13A and 13B show perspective and cross-sectional side
views, respectively, of yet another variation of imaging assembly
which may utilize a fluid suction system for minimizing the amount
of fluid injected into the patient's heart or other body lumen
during tissue visualization. Deployment catheter 190 in this
variation may define an inner tubular member 196 which may be
integrated with deployment catheter 190 or independently
translatable. Fluid delivery lumen 198 defined through member 196
may be fluidly connected to imaging hood 192, which may also define
one or more open channels 194 over its contact lip region. Fluid
pumped through fluid delivery lumen 198 may thus fill open area 202
to displace any blood or other fluids or objects therewithin. As
the clear fluid is forced out of open area 202, it may be sucked or
drawn immediately through one or more channels 194 and back into
deployment catheter 190. Tubular member 196 may also define one or
more additional working channels 200 for the passage of any tools
or visualization devices.
[0129] In deploying the imaging hood in the examples described
herein, the imaging hood may take on any number of configurations
when positioned or configured for a low-profile delivery within the
delivery catheter, as shown in the examples of FIGS. 14A to 14D.
These examples are intended to be illustrative and are not intended
to be limiting in scope. FIG. 14A shows one example in which
imaging hood 212 may be compressed within catheter 210 by folding
hood 212 along a plurality of pleats. Hood 212 may also comprise
scaffolding or frame 214 made of a super-elastic or shape memory
material or alloy, e.g., Nitinol, Elgiloy, shape memory polymers,
electroactive polymers, or a spring stainless steel. The shape
memory material may act to expand or deploy imaging hood 212 into
its expanded configuration when urged in the direction of the arrow
from the constraints of catheter 210.
[0130] FIG. 14B shows another example in which imaging hood 216 may
be expanded or deployed from catheter 210 from a folded and
overlapping configuration. Frame or scaffolding 214 may also be
utilized in this example. FIG. 14C shows yet another example in
which imaging hood 218 may be rolled, inverted, or everted upon
itself for deployment. In yet another example, FIG. 14D shows a
configuration in which imaging hood 220 may be fabricated from an
extremely compliant material which allows for hood 220 to be simply
compressed into a low-profile shape. From this low-profile
compressed shape, simply releasing hood 220 may allow for it to
expand into its deployed configuration, especially if a scaffold or
frame of a shape memory or superelastic material, e.g., Nitinol, is
utilized in its construction.
[0131] Another variation for expanding the imaging hood is shown in
FIGS. 15A and 15B which illustrates an helically expanding frame or
support 230. In its constrained low-profile configuration, shown in
FIG. 15A, helical frame 230 may be integrated with the imaging hood
12 membrane. When free to expand, as shown in FIG. 15B, helical
frame 230 may expand into a conical or tapered shape. Helical frame
230 may alternatively be made out of heat-activated Nitinol to
allow it to expand upon application of a current.
[0132] FIGS. 16A and 16B show yet another variation in which
imaging hood 12 may comprise one or more hood support members 232
integrated with the hood membrane. These longitudinally attached
support members 232 may be pivotably attached at their proximal
ends to deployment catheter 16. One or more pullwires 234 may be
routed through the length of deployment catheter 16 and extend
through one or more openings 238 defined in deployment catheter 16
proximally to imaging hood 12 into attachment with a corresponding
support member 232 at a pullwire attachment point 236. The support
members 232 may be fabricated from a plastic or metal, such as
stainless steel. Alternatively, the support members 232 may be made
from a superelastic or shape memory alloy, such as Nitinol, which
may self-expand into its deployed configuration without the use or
need of pullwires. A heat-activated Nitinol may also be used which
expands upon the application of thermal energy or electrical
energy. In another alternative, support members 232 may also be
constructed as inflatable lumens utilizing, e.g., PET balloons.
From its low-profile delivery configuration shown in FIG. 16A, the
one or more pullwires 234 may be tensioned from their proximal ends
outside the patient body to pull a corresponding support member 232
into a deployed configuration, as shown in FIG. 16B, to expand
imaging hood 12. To reconfigure imaging hood 12 back into its low
profile, deployment catheter 16 may be pulled proximally into a
constraining catheter or the pullwires 234 may be simply pushed
distally to collapse imaging hood 12.
[0133] FIGS. 17A and 17B show yet another variation of imaging hood
240 having at least two or more longitudinally positioned support
members 242 supporting the imaging hood membrane. The support
members 242 each have cross-support members 244 which extend
diagonally between and are pivotably attached to the support
members 242. Each of the cross-support members 244 may be pivotably
attached to one another where they intersect between the support
members 242. A jack or screw member 246 may be coupled to each
cross-support member 244 at this intersection point and a torquing
member, such as a torqueable wire 248, may be coupled to each jack
or screw member 246 and extend proximally through deployment
catheter 16 to outside the patient body. From outside the patient
body, the torqueable wires 248 may be torqued to turn the jack or
screw member 246 which in turn urges the cross-support members 244
to angle relative to one another and thereby urge the support
members 242 away from one another. Thus, the imaging hood 240 may
be transitioned from its low-profile, shown in FIG. 17A, to its
expanded profile, shown in FIG. 17B, and back into its low-profile
by torquing wires 248.
[0134] FIGS. 18A and 18B show yet another variation on the imaging
hood and its deployment. As shown, a distal portion of deployment
catheter 16 may have several pivoting members 250, e.g., two to
four sections, which form a tubular shape in its low profile
configuration, as shown in FIG. 18A. When pivoted radially about
deployment catheter 16, pivoting members 250 may open into a
deployed configuration having distensible or expanding membranes
252 extending over the gaps in-between the pivoting members 250, as
shown in FIG. 18B. The distensible membrane 252 may be attached to
the pivoting members 250 through various methods, e.g., adhesives,
such that when the pivoting members 250 are fully extended into a
conical shape, the pivoting members 250 and membrane 252 form a
conical shape for use as an imaging hood. The distensible membrane
252 may be made out of a porous material such as a mesh or PTFE or
out of a translucent or transparent polymer such as polyurethane,
PVC, Nylon, etc.
[0135] FIGS. 19A and 19B show yet another variation where the
distal portion of deployment catheter 16 may be fabricated from a
flexible metallic or polymeric material to form a radially
expanding hood 254. A plurality of slots 256 may be formed in a
uniform pattern over the distal portion of deployment catheter 16,
as shown in FIG. 19A. The slots 256 may be formed in a pattern such
that when the distal portion is urged radially open, utilizing any
of the methods described above, a radially expanded and
conically-shaped hood 254 may be formed by each of the slots 256
expanding into an opening, as shown in FIG. 19B. A distensible
membrane 258 may overlie the exterior surface or the interior
surface of the hood 254 to form a fluid-impermeable hood 254 such
that the hood 254 may be utilized as an imaging hood.
Alternatively, the distensible membrane 258 may alternatively be
formed in each opening 258 to form the fluid-impermeable hood 254.
Once the imaging procedure has been completed, hood 254 may be
retracted into its low-profile configuration.
[0136] Yet another configuration for the imaging hood may be seen
in FIGS. 20A and 20B where the imaging hood may be formed from a
plurality of overlapping hood members 260 which overlie one another
in an overlapping pattern. When expanded, each of the hood members
260 may extend radially outward relative to deployment catheter 16
to form a conically-shaped imaging hood, as shown in FIG. 20B.
Adjacent hood members 260 may overlap one another along an
overlapping interface 262 to form a fluid-retaining surface within
the imaging hood. Moreover, the hood members 260 may be made from
any number of biocompatible materials, e.g., Nitinol, stainless
steel, polymers, etc., which are sufficiently strong to optionally
retract surrounding tissue from the tissue region of interest.
[0137] Although it is generally desirable to have an imaging hood
contact against a tissue surface in a normal orientation, the
imaging hood may be alternatively configured to contact the tissue
surface at an acute angle. An imaging hood configured for such
contact against tissue may also be especially suitable for contact
against tissue surfaces having an unpredictable or uneven
anatomical geography. For instance, as shown in the variation of
FIG. 21A, deployment catheter 270 may have an imaging hood 272 that
is configured to be especially compliant. In this variation,
imaging hood 272 may be comprised of one or more sections 274 that
are configured to fold or collapse, e.g., by utilizing a pleated
surface. Thus, as shown in FIG. 21B, when imaging hood 272 is
contacted against uneven tissue surface T, sections 274 are able to
conform closely against the tissue. These sections 274 may be
individually collapsible by utilizing an accordion style
construction to allow conformation, e.g., to the trabeculae in the
heart or the uneven anatomy that may be found inside the various
body lumens.
[0138] In yet another alternative, FIG. 22A shows another variation
in which an imaging hood 282 is attached to deployment catheter
280. The contact lip or edge 284 may comprise one or more
electrical contacts 286 positioned circumferentially around contact
edge 284. The electrical contacts 286 may be configured to contact
the tissue and indicate affirmatively whether tissue contact was
achieved, e.g., by measuring the differential impedance between
blood and tissue. Alternatively, a processor, e.g., processor 98,
in electrical communication with contacts 286 may be configured to
determine what type of tissue is in contact with electrical
contacts 286. In yet another alternative, the processor 98 may be
configured to measure any electrical activity that may be occurring
in the underlying tissue, e.g., accessory pathways, for the
purposes of electrically mapping the cardiac tissue and
subsequently treating, as described below, any arrhythmias which
may be detected.
[0139] Another variation for ensuring contact between imaging hood
282 and the underlying tissue may be seen in FIG. 22B. This
variation may have an inflatable contact edge 288 around the
circumference of imaging hood 282. The inflatable contact edge 288
may be inflated with a fluid or gas through inflation lumen 289
when the imaging hood 282 is to be placed against a tissue surface
having an uneven or varied anatomy. The inflated circumferential
surface 288 may provide for continuous contact over the hood edge
by conforming against the tissue surface and facilitating imaging
fluid retention within hood 282.
[0140] Aside from the imaging hood, various instrumentation may be
utilized with the imaging and manipulation system. For instance,
after the field within imaging hood 12 has been cleared of the
opaque blood and the underlying tissue is visualized through the
clear fluid, blood may seep back into the imaging hood 12 and
obstruct the view. One method for automatically maintaining a clear
imaging field may utilize a transducer, e.g., an ultrasonic
transducer 290, positioned at the distal end of deployment catheter
within the imaging hood 12, as shown in FIG. 23. The transducer 290
may send an energy pulse 292 into the imaging hood 12 and wait to
detect back-scattered energy 294 reflected from debris or blood
within the imaging hood 12. If back-scattered energy is detected,
the pump may be actuated automatically to dispense more fluid into
the imaging hood until the debris or blood is no longer
detected.
[0141] Alternatively, one or more sensors 300 may be positioned on
the imaging hood 12 itself, as shown in FIG. 24A, to detect a
number of different parameters. For example, sensors 300 may be
configured to detect for the presence of oxygen in the surrounding
blood, blood and/or imaging fluid pressure, color of the fluid
within the imaging hood, etc. Fluid color may be particularly
useful in detecting the presence of blood within the imaging hood
12 by utilizing a reflective type sensor to detect back reflection
from blood. Any reflected light from blood which may be present
within imaging hood 12 may be optically or electrically transmitted
through deployment catheter 16 and to a red colored filter within
control electronics 118. Any red color which may be detected may
indicate the presence of blood and trigger a signal to the
physician or automatically actuate the pump to dispense more fluid
into the imaging hood 12 to clear the blood.
[0142] Alternative methods for detecting the presence of blood
within the hood 12 may include detecting transmitted light through
the imaging fluid within imaging hood 12. If a source of white
light, e.g., utilizing LEDs or optical fibers, is illuminated
inside imaging hood 12, the presence of blood may cause the color
red to be filtered through this fluid. The degree or intensity of
the red color detected may correspond to the amount of blood
present within imaging hood 12. A red color sensor can simply
comprise, in one variation, a phototransistor with a red
transmitting filter over it which can establish how much red light
is detected, which in turn can indicate the presence of blood
within imaging hood 12. Once blood is detected, the system may pump
more clearing fluid through and enable closed loop feedback control
of the clearing fluid pressure and flow level.
[0143] Any number of sensors may be positioned along the exterior
302 of imaging hood 12 or within the interior 304 of imaging hood
12 to detect parameters not only exteriorly to imaging hood 12 but
also within imaging hood 12. Such a configuration, as shown in FIG.
24B, may be particularly useful for automatically maintaining a
clear imaging field based upon physical parameters such as blood
pressure, as described above for FIGS. 10A and 10B.
[0144] Aside from sensors, one or more light emitting diodes (LEDs)
may be utilized to provide lighting within the imaging hood 12.
Although illumination may be provided by optical fibers routed
through deployment catheter 16, the use of LEDs over the imaging
hood 12 may eliminate the need for additional optical fibers for
providing illumination. The electrical wires connected to the one
or more LEDs may be routed through or over the hood 12 and along an
exterior surface or extruded within deployment catheter 16. One or
more LEDs may be positioned in a circumferential pattern 306 around
imaging hood 12, as shown in FIG. 25A, or in a linear longitudinal
pattern 308 along imaging hood 12, as shown in FIG. 25B. Other
patterns, such as a helical or spiral pattern, may also be
utilized. Alternatively, LEDs may be positioned along a support
member forming part of imaging hood 12.
[0145] In another alternative for illumination within imaging hood
12, a separate illumination tool 310 may be utilized, as shown in
FIG. 26A. An example of such a tool may comprise a flexible
intravascular delivery member 312 having a carrier member 314
pivotably connected 316 to a distal end of delivery member 312. One
or more LEDs 318 may be mounted along carrier member 314. In use,
delivery member 312 may be advanced through deployment catheter 16
until carrier member 314 is positioned within imaging hood 12. Once
within imaging hood 12, carrier member 314 may be pivoted in any
number of directions to facilitate or optimize the illumination
within the imaging hood 12, as shown in FIG. 26B.
[0146] In utilizing LEDs for illumination, whether positioned along
imaging hood 12 or along a separate instrument, the LEDs may
comprise a single LED color, e.g., white light. Alternatively, LEDs
of other colors, e.g., red, blue, yellow, etc., may be utilized
exclusively or in combination with white LEDs to provide for varied
illumination of the tissue or fluids being imaged. Alternatively,
sources of infrared or ultraviolet light may be employed to enable
imaging beneath the tissue surface or cause fluorescence of tissue
for use in system guidance, diagnosis, or therapy.
[0147] Aside from providing a visualization platform, the imaging
assembly may also be utilized to provide a therapeutic platform for
treating tissue being visualized. As shown in FIG. 27, deployment
catheter 320 may have imaging hood 322, as described above, and
fluid delivery lumen 324 and imaging lumen 326. In this variation,
a therapeutic tool such as needle 328 may be delivered through
fluid delivery lumen 324 or in another working lumen and advanced
through open area 332 for treating the tissue which is visualized.
In this instance, needle 328 may define one or several ports 330
for delivering drugs therethrough. Thus, once the appropriate
region of tissue has been imaged and located, needle 328 may be
advanced and pierced into the underlying tissue where a therapeutic
agent may be delivered through ports 330. Alternatively, needle 328
may be in electrical communication with a power source 334, e.g.,
radio-frequency, microwave, etc., for ablating the underlying
tissue area of interest.
[0148] FIG. 28 shows another alternative in which deployment
catheter 340 may have imaging hood 342 attached thereto, as above,
but with a therapeutic tool 344 in the configuration of a helical
tissue piercing device 344. Also shown and described above in FIGS.
7A and 7B for use in stabilizing the imaging hood relative to the
underlying tissue, the helical tissue piercing device 344 may also
be utilized to manipulate the tissue for a variety of therapeutic
procedures. The helical portion 346 may also define one or several
ports for delivery of therapeutic agents therethrough.
[0149] In yet another alternative, FIG. 29 shows a deployment
catheter 350 having an expandable imaging balloon 352 filled with,
e.g., saline 356. A therapeutic tool 344, as above, may be
translatable relative to balloon 352. To prevent the piercing
portion 346 of the tool from tearing balloon 352, a stop 354 may be
formed on balloon 352 to prevent the proximal passage of portion
346 past stop 354.
[0150] Alternative configurations for tools which may be delivered
through deployment catheter 16 for use in tissue manipulation
within imaging hood 12 are shown in FIGS. 30A and 30B. FIG. 30A
shows one variation of an angled instrument 360, such as a tissue
grasper, which may be configured to have an elongate shaft for
intravascular delivery through deployment catheter 16 with a distal
end which may be angled relative to its elongate shaft upon
deployment into imaging hood 12. The elongate shaft may be
configured to angle itself automatically, e.g., by the elongate
shaft being made at least partially from a shape memory alloy, or
upon actuation, e.g., by tensioning a pullwire. FIG. 30B shows
another configuration for an instrument 362 being configured to
reconfigure its distal portion into an off-axis configuration
within imaging hood 12. In either case, the instruments 360, 362
may be reconfigured into a low-profile shape upon withdrawing them
proximally back into deployment catheter 16.
[0151] Other instruments or tools which may be utilized with the
imaging system is shown in the side and end views of FIGS. 31A to
31C. FIG. 31A shows a probe 370 having a distal end effector 372,
which may be reconfigured from a low-profile shape to a curved
profile. The end effector 372 may be configured as an ablation
probe utilizing radio-frequency energy, microwave energy,
ultrasound energy, laser energy or even cryo-ablation.
Alternatively, the end effector 372 may have several electrodes
upon it for detecting or mapping electrical signals transmitted
through the underlying tissue.
[0152] In the case of an end effector 372 utilized for ablation of
the underlying tissue, an additional temperature sensor such as a
thermocouple or thermistor 374 positioned upon an elongate member
376 may be advanced into the imaging hood 12 adjacent to the distal
end effector 372 for contacting and monitoring a temperature of the
ablated tissue. FIG. 31B shows an example in the end view of one
configuration for the distal end effector 372 which may be simply
angled into a perpendicular configuration for contacting the
tissue. FIG. 31C shows another example where the end effector may
be reconfigured into a curved end effector 378 for increased tissue
contact.
[0153] FIGS. 32A and 32B show another variation of an ablation tool
utilized with an imaging hood 12 having an enclosed bottom portion.
In this variation, an ablation probe, such as a cryo-ablation probe
380 having a distal end effector 382, may be positioned through the
imaging hood 12 such that the end effector 382 is placed distally
of a transparent membrane or enclosure 384, as shown in the end
view of FIG. 32B. The shaft of probe 380 may pass through an
opening 386 defined through the membrane 384. In use, the clear
fluid may be pumped into imaging hood 12, as described above, and
the distal end effector 382 may be placed against a tissue region
to be ablated with the imaging hood 12 and the membrane 384
positioned atop or adjacent to the ablated tissue. In the case of
cryo-ablation, the imaging fluid may be warmed prior to dispensing
into the imaging hood 12 such that the tissue contacted by the
membrane 384 may be warmed during the cryo-ablation procedure. In
the case of thermal ablation, e.g., utilizing radio-frequency
energy, the fluid dispensed into the imaging hood 12 may be cooled
such that the tissue contacted by the membrane 384 and adjacent to
the ablation probe during the ablation procedure is likewise
cooled.
[0154] In either example described above, the imaging fluid may be
varied in its temperature to facilitate various procedures to be
performed upon the tissue. In other cases, the imaging fluid itself
may be altered to facilitate various procedures. For instance as
shown in FIG. 33A, a deployment catheter 16 and imaging hood 12 may
be advanced within a hollow body organ, such as a bladder filled
with urine 394, towards a lesion or tumor 392 on the bladder wall.
The imaging hood 12 may be placed entirely over the lesion 392, or
over a portion of the lesion. Once secured against the tissue wall
390, a cryo-fluid, i.e., a fluid which has been cooled to below
freezing temperatures of, e.g., water or blood, may be pumped into
the imaging hood 12 to cryo-ablate the lesion 390, as shown in FIG.
33B while avoiding the creation of ice on the instrument or surface
of tissue.
[0155] As the cryo-fluid leaks out of the imaging hood 12 and into
the organ, the fluid may be warmed naturally by the patient body
and ultimately removed. The cryo-fluid may be a colorless and
translucent fluid which enables visualization therethrough of the
underlying tissue. An example of such a fluid is Fluorinert.TM.
(3M, St. Paul, Minn.), which is a colorless and odorless
perfluorinated liquid. The use of a liquid such as Fluorinert.TM.
enables the cryo-ablation procedure without the formation of ice
within or outside of the imaging hood 12. Alternatively, rather
than utilizing cryo-ablation, hyperthermic treatments may also be
effected by heating the Fluorinert.TM. liquid to elevated
temperatures for ablating the lesion 392 within the imaging hood
12. Moreover, Fluorinert.TM. may be utilized in various other parts
of the body, such as within the heart.
[0156] FIG. 34A shows another variation of an instrument which may
be utilized with the imaging system. In this variation, a laser
ring generator 400 may be passed through the deployment catheter 16
and partially into imaging hood 12. A laser ring generator 400 is
typically used to create a circular ring of laser energy 402 for
generating a conduction block around the pulmonary veins typically
in the treatment of atrial fibrillation. The circular ring of laser
energy 402 may be generated such that a diameter of the ring 402 is
contained within a diameter of the imaging hood 12 to allow for
tissue ablation directly upon tissue being imaged. Signals which
cause atrial fibrillation typically come from the entry area of the
pulmonary veins into the left atrium and treatments may sometimes
include delivering ablation energy to the ostia of the pulmonary
veins within the atrium. The ablated areas of the tissue may
produce a circular scar which blocks the impulses for atrial
fibrillation.
[0157] When using the laser energy to ablate the tissue of the
heart, it may be generally desirable to maintain the integrity and
health of the tissue overlying the surface while ablating the
underlying tissue. This may be accomplished, for example, by
cooling the imaging fluid to a temperature below the body
temperature of the patient but which is above the freezing point of
blood (e.g., 2.degree. C. to 35.degree. C.). The cooled imaging
fluid may thus maintain the surface tissue at the cooled fluid
temperature while the deeper underlying tissue remains at the
patient body temperature. When the laser energy (or other types of
energy such as radio frequency energy, microwave energy, ultrasound
energy. etc.) irradiates the tissue, both the cooled tissue surface
as well as the deeper underlying tissue will rise in temperature
uniformly. The deeper underlying tissue, which was maintained at
the body temperature, will increase to temperatures which are
sufficiently high to destroy the underlying tissue. Meanwhile, the
temperature of the cooled surface tissue will also rise but only to
temperatures that are near body temperature or slightly above.
[0158] Accordingly, as shown in FIG. 34B, one example for treatment
may include passing deployment catheter 16 across the atrial septum
AS and into the left atrium LA of the patient's heart H. Other
methods of accessing the left atrium LA may also be utilized. The
imaging hood 12 and laser ring generator 400 may be positioned
adjacent to or over one or more of the ostium OT of the pulmonary
veins PV and the laser generator 400 may ablate the tissue around
the ostium OT with the circular ring of laser energy 402 to create
a conduction block. Once one or more of the tissue around the
ostium OT have been ablated, the imaging hood 12 may be
reconfigured into a low profile for removal from the patient heart
H.
[0159] One of the difficulties in treating tissue in or around the
ostium OT is the dynamic fluid flow of blood through the ostium OT.
The dynamic forces make cannulation or entry of the ostium OT
difficult. Thus, another variation on instruments or tools
utilizable with the imaging system is an extendible cannula 410
having a cannula lumen 412 defined therethrough, as shown in FIG.
35A. The extendible cannula 410 may generally comprise an elongate
tubular member which may be positioned within the deployment
catheter 16 during delivery and then projected distally through the
imaging hood 12 and optionally beyond, as shown in FIG. 35B.
[0160] In use, once the imaging hood 12 has been desirably
positioned relative to the tissue, e.g., as shown in FIG. 35C
outside the ostium OT of a pulmonary vein PV, the extendible
cannula 410 may be projected distally from the deployment catheter
16 while optionally imaging the tissue through the imaging hood 12,
as described above. The extendible cannula 410 may be projected
distally until its distal end is extended at least partially into
the ostium OT. Once in the ostium OT, an instrument or energy
ablation device may be extended through and out of the cannula
lumen 412 for treatment within the ostium OT. Upon completion of
the procedure, the cannula 410 may be withdrawn proximally and
removed from the patient body. The extendible cannula 410 may also
include an inflatable occlusion balloon at or near its distal end
to block the blood flow out of the PV to maintain a clear view of
the tissue region. Alternatively, the extendible cannula 410 may
define a lumen therethrough beyond the occlusion balloon to bypass
at least a portion of the blood that normally exits the pulmonary
vein PV by directing the blood through the cannula 410 to exit
proximal of the imaging hood.
[0161] Yet another variation for tool or instrument use may be seen
in the side and end views of FIGS. 36A and 36B. In this variation,
imaging hood 12 may have one or more tubular support members 420
integrated with the hood 12. Each of the tubular support members
420 may define an access lumen 422 through which one or more
instruments or tools may be delivered for treatment upon the
underlying tissue. One particular example is shown and described
above for FIG. 7C.
[0162] Various methods and instruments may be utilized for using or
facilitating the use of the system. For instance, one method may
include facilitating the initial delivery and placement of a device
into the patient's heart. In initially guiding the imaging assembly
within the heart chamber to, e.g., the mitral valve MV. a separate
guiding probe 430 may be utilized, as shown in FIGS. 37A and 37B.
Guiding probe 430 may, for example, comprise an optical fiber
through which a light source 434 may be used to illuminate a distal
tip portion 432. The tip portion 432 may be advanced into the heart
through, e.g., the coronary sinus CS, until the tip is positioned
adjacent to the mitral valve MV. The tip 432 may be illuminated, as
shown in FIG. 37A, and imaging assembly 10 may then be guided
towards the illuminated tip 432, which is visible from within the
atrial chamber, towards mitral valve MV.
[0163] Aside from the devices and methods described above, the
imaging system may be utilized to facilitate various other
procedures. Turning now to FIGS. 38A and 38B, the imaging hood of
the device in particular may be utilized. In this example, a
collapsible membrane or disk-shaped member 440 may be temporarily
secured around the contact edge or lip of imaging hood 12. During
intravascular delivery, the imaging hood 12 and the attached member
440 may both be in a collapsed configuration to maintain a low
profile for delivery. Upon deployment, both the imaging hood 12 and
the member 440 may extend into their expanded configurations.
[0164] The disk-shaped member 440 may be comprised of a variety of
materials depending upon the application. For instance, member 440
may be fabricated from a porous polymeric material infused with a
drug eluting medicament 442 for implantation against a tissue
surface for slow infusion of the medicament into the underlying
tissue. Alternatively, the member 440 may be fabricated from a
non-porous material, e.g., metal or polymer, for implantation and
closure of a wound or over a cavity to prevent fluid leakage. In
yet another alternative, the member 440 may be made from a
distensible material which is secured to imaging hood 12 in an
expanded condition. Once implanted or secured on a tissue surface
or wound, the expanded member 440 may be released from imaging hood
12. Upon release, the expanded member 440 may shrink to a smaller
size while approximating the attached underlying tissue, e.g., to
close a wound or opening.
[0165] One method for securing the disk-shaped member 440 to a
tissue surface may include a plurality of tissue anchors 444. e.g.,
barbs, hooks, projections, etc., which are attached to a surface of
the member 440. Other methods of attachments may include adhesives,
suturing, etc. In use, as shown in FIGS. 39A to 39C, the imaging
hood 12 may be deployed in its expanded configuration with member
440 attached thereto with the plurality of tissue anchors 444
projecting distally. The tissue anchors 444 may be urged into a
tissue region to be treated 446, as seen in FIG. 39A, until the
anchors 444 are secured in the tissue and member 440 is positioned
directly against the tissue, as shown in FIG. 39B. A pullwire may
be actuated to release the member 440 from the imaging hood 12 and
deployment catheter 16 may be withdrawn proximally to leave member
440 secured against the tissue 446.
[0166] Another variation for tissue manipulation and treatment may
be seen in the variation of FIG. 40A, which illustrates an imaging
hood 12 having a deployable anchor assembly 450 attached to the
tissue contact edge 22. FIG. 40B illustrates the anchor assembly
450 detached from the imaging hood 12 for clarity. The anchor
assembly 450 may be seen as having a plurality of discrete tissue
anchors 456, e.g., barbs, hooks, projections, etc., each having a
suture retaining end, e.g., an eyelet or opening 458 in a proximal
end of the anchors 456. A suture member or wire 452 may be
slidingly connected to each anchor 456 through the openings 458 and
through a cinching element 454, which may be configured to slide
uni-directionally over the suture or wire 452 to approximate each
of the anchors 456 towards one another. Each of the anchors 456 may
be temporarily attached to the imaging hood 12 through a variety of
methods. For instance, a pullwire or retaining wire may hold each
of the anchors within a receiving ring around the circumference of
the imaging hood 12. When the anchors 456 are released, the
pullwire or retaining wire may be tensioned from its proximal end
outside the patient body to thereby free the anchors 456 from the
imaging hood 12.
[0167] One example for use of the anchor assembly 450 is shown in
FIGS. 41A to 41D for closure of an opening or wound 460, e.g.,
patent foramen ovale (PFO). The deployment catheter 16 and imaging
hood 12 may be delivered intravascularly into, e.g., a patient
heart. As the imaging hood 12 is deployed into its expanded
configuration, the imaging hood 12 may be positioned adjacent to
the opening or wound 460, as shown in FIG. 41A. With the anchor
assembly 450 positioned upon the expanded imaging hood 12,
deployment catheter 16 may be directed to urge the contact edge of
imaging hood 12 and anchor assembly 450 into the region surrounding
the tissue opening 460, as shown in FIG. 41B. Once the anchor
assembly 450 has been secured within the surrounding tissue, the
anchors may be released from imaging hood 12 leaving the anchor
assembly 450 and suture member 452 trailing from the anchors, as
shown in FIG. 41C. The suture or wire member 452 may be tightened
by pulling it proximally from outside the patient body to
approximate the anchors of anchor assembly 450 towards one another
in a purse-string manner to close the tissue opening 462, as shown
in FIG. 41D. The cinching element 454 may also be pushed distally
over the suture or wire member 452 to prevent the approximated
anchor assembly 450 from loosening or widening.
[0168] Another example for an alternative use is shown in FIG. 42,
where the deployment catheter 16 and deployed imaging hood 12 may
be positioned within a patient body for drawing blood 472 into
deployment catheter 16. The drawn blood 472 may be pumped through a
dialysis unit 470 located externally of the patient body for
filtering the drawn blood 472 and the filtered blood may be
reintroduced back into the patient.
[0169] Yet another variation is shown in FIGS. 43A and 43B, which
show a variation of the deployment catheter 480 having a first
deployable hood 482 and a second deployable hood 484 positioned
distal to the first hood 482. The deployment catheter 480 may also
have a side-viewing imaging element 486 positioned between the
first and second hoods 482, 484 along the length of the deployment
catheter 480. In use, such a device may be introduced through a
lumen 488 of a vessel VS, where one or both hoods 482, 484 may be
expanded to gently contact the surrounding walls of vessel VS. Once
hoods 482, 484 have been expanded, the clear imaging fluid may be
pumped in the space defined between the hoods 482, 484 to displace
any blood and to create an imaging space 490, as shown in FIG. 43B.
With the clear fluid in-between hoods 482, 484, the imaging element
486 may be used to view the surrounding tissue surface contained
between hoods 482, 484. Other instruments or tools may be passed
through deployment catheter 480 and through one or more openings
defined along the catheter 480 for additionally performing
therapeutic procedures upon the vessel wall.
[0170] Another variation of a deployment catheter 500 which may be
used for imaging tissue to the side of the instrument may be seen
in FIGS. 44A to 45B. FIGS. 44A and 44B show side and end views of
deployment catheter 500 having a side-imaging balloon 502 in an
un-inflated low-profile configuration. A side-imaging element 504
may be positioned within a distal portion of the catheter 500 where
the balloon 502 is disposed. When balloon 502 is inflated, it may
expand radially to contact the surrounding tissue, but where the
imaging element 504 is located, a visualization field 506 may be
created by the balloon 502, as shown in the side, top, and end
views of FIGS. 45A to 45B, respectively. The visualization field
506 may simply be a cavity or channel which is defined within the
inflated balloon 502 such that the visualization element 504 is
provided an image of the area within field 506 which is clear and
unobstructed by balloon 502.
[0171] In use, deployment catheter 500 may be advanced
intravascularly through vessel lumen 488 towards a lesion or tumor
508 to be visualized and/or treated. Upon reaching the lesion 508,
deployment catheter 500 may be positioned adjacently to the lesion
508 and balloon 502 may be inflated such that the lesion 508 is
contained within the visualization field 506. Once balloon 502 is
fully inflated and in contact against the vessel wall, clear fluid
may be pumped into visualization field 506 through deployment
catheter 500 to displace any blood or opaque fluids from the field
506, as shown in the side and end views of FIGS. 46A and 46B,
respectively. The lesion 508 may then be visually inspected and
treated by passing any number of instruments through deployment
catheter 500 and into field 506.
[0172] In controlling the advancement and articulation of any of
the delivery catheters described herein, the catheter may be
manually controlled or robotically-controlled, as mentioned above.
Examples of robotically-controlled catheter systems which utilize
precision motion control mechanisms are shown and described in U.S.
Pat. App. 2006/0084945 A1 and U.S. Pat. No. 7,090,683, each of
which is incorporated herein by reference in its entirety.
Generally, a visualization hood may be attached or coupled to the
distal end of a catheter articulated or controlled by precision
motion control mechanisms. The articulatable neck portion of the
shaft, located proximally of the visualization hood, may be
comprised of an assembly of links fabricated, e.g., from stainless
steel, plastics, etc., that allow the neck portion to be
articulated in multiple planes. One or more, e.g., four, pullwires
may be routed through the neck and/or shaft such that they
terminate at the hood attachment, while the proximal end or ends of
the pullwires may be routed through the links to a proximal end of
the catheter. Combinations of retraction and/or extension motions
of these pullwires may be utilized to steer the neck portion to
articulate the hood in multiple directions as desired by the
operator.
[0173] The proximal ends of the pullwires are threaded through a
pulley assembly and terminated in rotatable spools. Rotating these
spools will either retract the pullwires or release more slack into
the catheter to enable steering as appropriate. The pullwire spools
are further driven by control elements such as low speed motors,
which in turn, may be driven by a central processing unit. Precise
and consistent low speed rotation of the spools controlled by the
central processing unit and the motors will enable the pullwires to
be retracted or released with high precision. This will translate
into precision articulation and motion control of the tissue
visualization hood.
[0174] Referring now to FIG. 47A, an example of a robotic guide
instrument 600 is illustrated having two control element interface
assemblies configured to drive, e.g., four control elements 606,
e.g., pullwires. Rotation of the pulleys in a first direction may
spool and proximally displace one control element 606, while
unspooling in a second opposite direction may distally displace a
complementary control element 606 to deflect the distal end of the
deployment catheter 14 in the opposite direction. Tension may be
maintained in the control elements 606 via pre-tensioning or
pre-stressing the elements to prevent excess slack. Tension may
also be maintained on the control elements 606 using a slotted
guide instrument base 602 which forms one or more slots 604 through
which the control elements 606 may remain taut.
[0175] FIG. 47B illustrates the robotic guide instrument 600 having
hood 12 positioned upon deployment catheter 16 with an inflatable
balloon or membrane 608 optionally disposable within or upon hood
12 and an instrument advanced through catheter 16 and into hood 12.
As schematically illustrated, the robotic guide instrument 600, and
optionally the instruments advanced through hood 12, may be
controlled via a computer or processor 612 to control the
articulation of the hood 12 as well as other functions. The
treatment instrument may include any number of instruments, e.g.,
ablation tools, a piercing needle 610, etc., which may be advanced
through the hood for treating the underlying tissue. Examples of
instruments as well as alternative configurations for hood 12 are
shown and described in further detail in the following U.S. patent
application Ser. Nos. 11/775,771 and 11 /775,837 both filed Jul.
10, 2007, and 11/928,267 filed Jul. 25, 2007, each of which is
incorporated herein by reference in its entirety.
[0176] FIG. 47C illustrates an example of how a robotic guide
instrument may be utilized with a visualization system. Generally,
a user may interface with input device 651, which may utilize any
number of different interfaces, e.g., handle, joystick, etc., by
which the user may transmit desired commands to processor 631.
Processor 631 may receive the commands and transmit the appropriate
drive signals to the catheter and computer-controlled guidance
assembly 639 which may then control the hood, imaging systems,
fluid purging systems, etc. in accordance with the received
commands from the user. When the catheter and/or hood interfaces
with the surrounding tissue, the resulting force or tracking
feedback may be optionally sensed by guidance assembly 639 and
transmitted back to processor 631, which in turn may signal or
indicate to the user via force feedback through input device 651 or
some other force or visual feedback. Moreover, the image data
captured by the imaging element within or along hood 12 may also be
received by guidance assembly 639 and transmitted to processor 631,
which may receive the image data for processing and display upon a
tissue surface image display 649 to the user.
[0177] Catheter and computer-controlled guidance assembly 639 may
comprise several sub-systems for controlling each of a number of
different functions, for instance (amongst other sub-systems), an
articulation drive 641 for controlling a movement of the catheter
16 and/or hood 12, a movement tracking system 643 for tracking a
position and/or orientation of the catheter 16 and/or hood 12
within the patient body, an imaging clement system 645 for
controlling the visualization features, as well as a blood
displacement system 647 for controlling and/or tracking an infusion
of transparent fluid into the hood 12.
[0178] Processor 631 may also be configured to handle several
different processing functions to process various data. For
instance, processor 631 may be configured to input commands
registered with tissue surface images 633 as received from input
device 651, as well as process catheter position data 635 based
upon catheter tracking feedback signals as received from the
movement tracking system 643 from guidance assembly 639. Moreover,
processor 631 may be configured to process desired catheter
articulations 637 in accordance with the commands received from the
input device 651 such that drive signals are generated by processor
631 and transmitted to the articulation drive 641 in guidance
assembly 639 to control the movements of the catheter and/or hood
in a desired manner.
[0179] FIG. 48A illustrates a perspective view of a variation of a
robotic control assembly showing base 602 having four proximal
drive assemblies 630 attached thereupon where each assembly 630 may
control a corresponding control element, e.g., pullwire, for
controlling an articulation of hood 12 positioned upon deployment
catheter 16. Delivery catheter or sheath 14 may be attached or
otherwise coupled to base 602 or to sheath instrument 632 having an
instrument base 636, which may also have a drive assembly 630
rotatably positioned thereon. The control elements attached to
their respective drive assembly 630 may each extend through
delivery catheter 14 and couple to the hood 12, as described below,
to bend the distal end of the deployment catheter 16 and/or hood 12
itself in any number of directions by displacing one of the control
elements in the proximal direction to deflect the distal end of the
catheter member in the predetermined direction.
[0180] Catheter 14 may be coupled to instrument base 636 such that
the drive assembly 630 may be used to control a retraction or
advancement of the catheter 14 relative to hood 12 to control the
expansion or collapse of hood 12. FIG. 48B shows a detail
perspective view of the distal end of catheter 16 extending from
delivery catheter 14 and articulation of the hood 12 relative to
the catheter 16. In one variation, hood 12 may utilize imaging
element 620, e.g., CMOS, CCD imager, etc., positioned off-axis
relative to a longitudinal axis of catheter 16 and attached along
one or more support struts 622 within hood 12. Hood 12 may be
connected to hood base 640 which is pivotable in a first plane via
hinge or pivot 642. Hood base 640 may itself be pivotable in a
second plane via hinge or pivot 644 and the distal end of
deployment catheter 16 may further define an articulatable section
638, which may allow its distal end to articulate within a plane
when urged by the one or more control elements.
[0181] FIG. 48C illustrates a perspective view of another variation
of a robotic control assembly having an inflatable imaging balloon
653 assembly. As shown, imaging balloon 653 may be positioned upon
articulatable deployment catheter 16 and may further include a
separate anchoring balloon 655 positioned upon support catheter 657
distally of imaging balloon 653. Support catheter 657 may extend
through both anchoring balloon 655 and imaging balloon 653 and
define a lumen 659 therethrough for accessing the tissue regions
with any number of instruments 667. In use, support catheter 657
and anchoring balloon 655 (in its deflated state) may be advanced
into a vessel lumen, e.g., through the ostium of a pulmonary vein,
where anchoring balloon 655 may be inflated into contact against
the surrounding vessel walls. With anchoring balloon 655 inflated,
support catheter 657 may be independently translatable with respect
to imaging balloon 653 (which may be inflated prior to, during, or
after anchoring of the anchoring balloon 655) to allow for
positional adjustment between imaging balloon 653 and the tissue
surrounding the ostium.
[0182] Imaging balloon 653 may be inflated with a transparent fluid
or gas, as described above, and may be further supported
structurally by one or more support struts 665 extending distally
from catheter 16 within or along a proximal portion of imaging
balloon 653. During introduction and/or advancement through the
patient body, support struts 665 may be collapsed along with
imaging balloon 653 into a low-profile configuration and when
deployed, balloon 653 may be inflated and support struts 665 may
extend radially relative to catheter 16 to support imaging balloon
653. Additionally, support struts 665 may also support one or more
light sources 661, e.g., light emitting diodes, optical fibers,
etc. to provide illumination through imaging balloon 653 for
viewing the underlying contacted tissue. Imaging element 663, as
above, may also be supported along or upon a support strut 665 for
viewing the tissue region through balloon 653 as well.
[0183] A partially disassembled view of the control clement 606
spooled around a respective drive assembly 630 is illustrated in
the perspective view of FIG. 49. As shown, each assembly 630 may
comprise an axle 650 about which assembly 630 may rotate in a first
direction to spool, and thus proximally displace an attached
control element 606 to deflect the distal end of catheter 16 is a
first direction, or rotate in a second opposite direction to
unspool, and thus distally displace the attached control element
606 to deflect the distal end of catheter 16 in a second opposite
direction.
[0184] The guide instrument 662 and sheath instrument 632 having
deployment catheter 16 extending distally therefrom with hood 12
articulatably disposed upon the distal end of catheter 16 is
illustrated in the perspective assembly view of FIG. 50. Both guide
instrument 662 and instrument guide 632 are illustrated mounted
upon instrument driver 660, which functions as a platform.
Instrument driver 660 may also provide additional degrees of
precision control movements for the visualization catheter system.
FIG. 51 shows a partial disassembled perspective view of the
instrument driver 660 assembly illustrating the main housing
structure 670 underlying the assembly. As illustrated, cams and
motors may be controlled by one or more electronics boards 672
which may be coupled to the main housing structure 670.
[0185] In yet another variation of a mechanism which provides
precision steering and articulation of the hood 12 is shown in the
perspective assembly view of FIG. 52A. A precision control drive
unit 680 may be attached to delivery catheter 14 and/or deployment
catheter 16 for providing articulation control. FIG. 52B
illustrates a detailed perspective view of the distal end of one
variation of deployment catheter 16 having the articulatable
section 638. Hinge or pivot 642 and 644 may provide for
articulation in at least two planes transverse to one another for
viewing tissue structures via imaging element 620 positioned within
hood 12, as described above. FIG. 53 illustrates an example of a
simplified assembly view of the mechanisms within control drive
unit 680 for controlling the articulation of hood 12. As shown, one
or more pullwires 682 may be routed through catheter 14 to hood 12
with their proximal ends coupled to one or more cams 684 or gears.
These cams 684 may be rotatably coupled to one or more drive wheels
686, which are in turn in communication through control cables 688
to (optional) gearing 692 of motor driver 690.
[0186] The examples illustrating precision control assemblies for
articulating the hood 12 and/or catheter 16 are further described
in detail in U.S. Pat. App. 2006/0084945 A1 and U.S. Pat. No.
7,090,683, each of which has been incorporated above in their
entirety.
[0187] In enabling the precision control assemblies to steer hood
12 and/or catheter 16 in multiple degrees of freedom, various
couplings between hood 12 and catheter 16 may be provided. One
variation is illustrated in the detail perspective view of FIGS.
54A and 54B, which show an assembled view and exploded assembly
view, respectively. In this variation, hood 12, having imaging
element 620 positioned therewithin in an off-axis location, may be
coupled or otherwise attached to hood base 640, which itself is
pivotably coupled via hood mating portion 706 connected to
receiving portion 708 via pin 710 to allow hood 12 to articulate
within a first plane. Receiving portion 708 may also be pivotably
coupled to receiving portion 702 via pin 704 to allow hood 12 to
articulate within a second plane transverse to the first plane. The
receiving portion 708 may also have one or more pullwire
termination points 700 to which one or more pullwires 682 may be
terminated.
[0188] FIGS. 55A and 55C shows another variation where a pair of
pullwires 682 may steer a first planarly articulatable spine
section 720 located near or at the distal end of deployment
catheter 16. A second pair of pullwires 682 may steer hood base 640
and hood 12 in a second plane transverse to the first plane. The
steerable spine section 720 may comprise a spine segment 722 having
multiple cut-outs or reduced sections 724 along either side of the
spine segment 722 such that the spine section 720 may bend in a
plane by flexing to either side of the reduced sections 724 while
maintaining structural integrity by the spine segment 722, as
illustrated in the detail view of FIG. 55B. Spine section 720 may
be comprised of various materials, e.g., stainless steel, PEEK or
hard plastics, through machining, molding or metal injection
molding. Moreover, stainless steel cables, Nitinol, elgiloy, or
tungsten wires can be used for pullwires. The section 720 can be
alternatively constructed as bump links, pinned links, ring links,
laser cut tubes, fish bone spine links, slit tubes or double
durometer tubes, etc., may also be steered using various mechanisms
such as single bend steering, double bend steering with two or more
pullwires, multi-way bend steering, and/or steering through
multiple variations of catheter-sheath interactions.
[0189] FIGS. 56A and 56C illustrate yet another variation of
steering mechanisms in the perspective assembly and exploded
assembly views. In this variation, a fully articulatable spine
section 730 may be included near or at the distal end of deployment
catheter 16, as above, where the section 730 includes a central
spine 734 having multiple cut-outs or reduced sections 732
circumferentially defined about central spine 734, as illustrated
in FIG. 56B. Having the reduced sections 732 defined entirely
around spine 734 enables full articulation of hood 12 about spine
734 rather than being limited for movement within a plane.
[0190] While utilizing a computer-controller for articulating the
assembly, the computer may also track the movement of hood 12
within a patient body, e.g., within the left atrial chamber of the
heart, such that the location and position relative to an
anatomical landmark, e.g., the pulmonary veins, are known at any
given time. Other alternative mechanisms may also be utilized to
track and/or record the position of hood 12 within the body at any
given time.
[0191] For instance, FIG. 57A shows a perspective view of one such
variation where a ferromagnetic ring 740 may be attached
circumferentially around the lip of hood 12. Such a configuration
may be utilized in conjunction with conventional magnetic
navigation systems, such as the NIOBE.RTM. system developed by
Stereotaxis, Inc. (Saint Louis, Mo.), as illustrated in the
perspective view of FIG. 57B. An example of such a magnetic
navigation system is shown and described in U.S. Pat. No. 7,019,610
(Creighton et al.) which is incorporated herein by reference in its
entirety. Generally, an arrangement of two magnets 746, 748 may be
positioned externally to the patient. With external control by an
operator, the two magnets 746, 748 may swing into position on each
side of the patient creating a magnetic field that directs and
digitally controls either the distal tip of the tissue
visualization catheter or, in this case, the ferromagnetic ring 740
positioned about the lip of hood 12. By rotating and moving the
external magnets 746, 748 to change the direction of the magnetic
field, the system automatically controls the catheter advancement
and retraction of the visualization catheter, eliminating any
pulling or pushing on the device. This may be particularly
advantageous when the tissue visualization catheter is threaded
through tortuous pathways where force transmission is greatly
reduced, consequently affecting accuracy in navigational control
that requires the pushing or pulling of the sheath or navigation
that requires steering internal pullwires.
[0192] FIG. 58 shows a perspective view of yet another variation of
the tissue visualization catheter which is configured to detect the
position and/or orientation of the hood 12 through the use of
existing ultrasound technologies as described in, e.g., U.S. Pat.
No. 5,515,853, which is incorporated herein by reference in its
entirety. As shown, a first 750 and second 752 ultrasound signal
transducer may be symmetrically attached to the hood 12 around the
circumference of the lip of hood 12, while a third ultrasound
transducer 754 may be placed between the tip of the deployment
catheter 16 and the proximal end of the hood 12.
[0193] A ferromagnetic ring or an electromagnetic coil 740 that is
able to interact with a magnetic field to pull the hood towards a
tissue surface may also be attached to the circumference of the
hood 12. Alternatively, the struts 758 supporting hood 12 may be
made of a ferromagnetic material where one or more of the struts
758 may have electromagnetic coils 756 wound around the struts 758,
as shown in the perspective view of FIG. 59. In yet another
alternative, a ferromagnetic disc 760 positioned upon a support
member 762 extending through hood 12 may also be utilized, as shown
in the perspective view of FIG. 60. In these or other variations of
hood 12, a circumferential balloon 742 which is inflatably
positioned within hood 12 and which defines a lumen or channel 744
through the inflated balloon 742 may be optionally utilized. Such a
balloon 742 is described in further detail in U.S. patent
application Ser. No. 11/775,771 filed Jul. 10, 2007, which is
incorporated herein by reference in its entirety.
[0194] In either case, the ferromagnetic or electromagnetic feature
and the ultrasound signal transducers 750, 752, 754 along hood 12
may be used with a position sensor assembly 770, as shown in the
perspective view of FIG. 61. Position sensor assembly 770 may
generally comprise a plate 772 made of radio-transparent material
which may be positioned externally of a patient along a skin
surface proximate or adjacent to where the hood 12 is to be
controlled or tracked within the patient body. Plate 772 may have
three or more ultrasound transducers 778, 780, 782 positioned along
the plate surface separated by a known distance from one another.
An electromagnet 776 attached to handle 774 may be slidably
positioned within plate 772 for controlling a position of hood 12
within the patient body, as described below.
[0195] Generally, each of the ultrasound transducers 750, 752, 754
positioned along hood 12 may communicate with the ultrasound
transducers 778, 780, 782 on the plate 772 to determine their
relative distances from one other by measuring the time between
transmission and detection of the ultrasound signals, as
illustrated in FIG. 62. By triangulation methods, the position of
each transducer along hood 12 relative to each transducer along
plate 772, the three-dimensional orientation and position of the
hood 12 within the patient body may be computationally determined
by a processor and displayed graphically or otherwise to the user.
The user may determine an orientation of the hood 12, for instance
if the hood 12 is facing the external plate 772 within the patient
body, when 750 and 752 are of equal distance to the plate 772.
Similarly using the same triangulation method, the position of the
hood 12 can be determined. Moreover, knowing which quadrant 790,
792, 794, 796 of the plate the hood 12 is relatively positioned may
be utilized in differentiating between particular anatomical
features, e.g., determining which of the four pulmonary veins the
user may be viewing in a patient's heart utilizing the imaging
element within hood 12, as described above.
[0196] Detailed examples are further shown and described in U.S.
Pat. No. 5,515,853, which is incorporated herein above.
Additionally, although three transducers are illustrated in the
example on hood 12 as well as plate 772, additional transducers may
be optionally utilized.
[0197] Moreover, in activating the electromagnet 776, e.g., by a
foot pedal, the ferromagnetic element located on the hood 12 may be
drawn via magnetic attraction towards the externally located plate
772 such that hood 12 is consequently drawn against the internal
tissue surface. By drawing the hood 12 against the internal tissue
surface, hood 12 may be positioned or articulated against the
tissue surface by the externally located handle 774 and
electromagnet 776 to facilitate movement of the hood 12 along
tissue walls.
[0198] An example is illustrated in FIGS. 63A to 63C which shows
hood 12 having circumferential ferromagnetic ring 740 positioned
thereon located within the left atrium LA of heart H. In placing
plate 772 of assembly 770 against the external skin surface S of
the patient body (e.g., behind the back of the patient, in a
position directly below the heart H, or any other position on the
patient body where a visualization catheter is to be advanced
along, into, or through an underlying organ or body lumen), a layer
of ultrasound coupling gel may be applied between the skin S and
the external plate 772, to ensure that ultrasound signals are
conducted efficiently. After entry of hood 12 within left atrium
LA, the orientation and position of the hood 12 may be determined
via triangulation relative to plate assembly 770, as shown in FIG.
63A. Upon orienting the hood 12, in a desired orientation and/or
position, the movable electromagnet 776 in the external plate 772
can be magnetized, e.g., by stepping on a foot pedal, to draw the
electromagnetic ring 740 and hood 12 towards the tissue wall, as
shown in FIG. 63B. With the hood 12 positioned upon the tissue
wall, handle 774 and electromagnet 776 may be moved in a direction
800 within plate 772 to "walk" or move hood 12 along the tissue
wall in a corresponding direction 800'. While hood 12 is drawn
against the tissue wall, the open area may be purged of blood and
the underlying tissue may be viewed through imaging element 620, as
described above.
[0199] Another variation is illustrated in the partial
cross-sectional view of FIG. 64, which illustrates an example where
rather than utilizing ultrasound transducers along an externally
located plate, a catheter 810 having at least three transducers
812, 814, 816 at known distances from one another may be
intravascularly advanced, e.g., into the coronary sinus CS of a
patient heart and positioned such that the transducers are located
about the mitral valve. Temporarily positioning the transducers
812, 814, 816 within the coronary sinus CS, where they are in
closer proximity with the transducers on the hood 12, may reduce
the loss of ultrasound signals to the environment as compared to
having transducers placed outside the body. Moreover, having the
transducers communicating within the body also removes the need for
ultrasound coupling gel to be applied on the patient's skin.
[0200] The applications of the disclosed invention discussed above
are not limited to certain treatments or regions of the body, but
may include any number of other treatments and areas of the body.
Modification of the above-described methods and devices for
carrying out the invention, and variations of aspects of the
invention that are obvious to those of skill in the arts are
intended to be within the scope of this disclosure. Moreover,
various combinations of aspects between examples are also
contemplated and are considered to be within the scope of this
disclosure as well.
* * * * *